Prince William has revealed that he was engulfed by a dark cloud of anguish and depression after witnessing the aftermath of a devastating accident.
In a remarkable display of candour, the Duke vividly describes how his torment left him feeling as if 'the whole world was dying'.
His mental health crisis came after he helped to save the life of a gravely injured boy only a few years older than his son, Prince George, while working as a helicopter pilot for the air ambulance service.
In an extraordinarily frank podcast to be released tomorrow, the future King describes how he was deeply affected by what he experienced that day.
Overwhelmed by depressive feelings, he says it was as if 'something had changed' inside him.
Weeks later his despair intensified. As he describes it, it was 'like someone had put a key in a lock and opened it without me giving permission to do that'.
He adds: 'You just feel everyone's pain, everyone's suffering. And that's not me. I've never felt that before.'
Prince William gave a remarkable insight into his state of mind in an intimate 38-minute programme entitled Prince William: Time To Walk (pictured), recorded for an Apple audio series in which celebrities share memories and pick three favourite songs while taking a stroll.
The Prince describes how talking to colleagues and meeting the boy's family enabled him to conquer his demons over time.
It is understood that William was referring to a car accident which left five-year-old Bobby Hughes brain damaged in 2017.
Last night, the boy's mother, Carly, 40, said: 'William told us how it affected him as a father and how he felt our pain.'
'He's amazing, a credit to our country... I've looked into his eyes and, genuinely, he has got a kind heart.'
The Prince gave a remarkable insight into his state of mind in an intimate 38-minute programme entitled Prince William: Time To Walk, recorded for an Apple audio series in which celebrities share memories and pick three favourite songs while taking a stroll.
William chose to walk three miles on the Sandringham estate in Norfolk between St Mary Magdalene Church and his home at Anmer Hall – the route he normally takes with his family on Christmas Day.
As well as his mental trauma, he speaks movingly of personal moments that have shaped his life.
In a wide-ranging monologue, the Duke describes:
William likens the intimate podcast to 'a walk with my best mate or my wife', and listeners can hear his footsteps as he walks along describing the animals in fields around his home.
The deeply personal nature of William's podcast marks a dramatic departure from the more formal and traditional style of communication from senior members of the Royal Family.
Of all the revelations, it is his frank disclosures about his mental health that are likely to startle listeners the most.
Last night, a royal source said: 'You really don't hear this sort of interview very often. It is a deeply significant insight into the Duke of Cambridge, not just as a member of the Royal family but as a person.'
The recording comes at an intriguing time for the future of the Monarchy.
William likens the intimate podcast to 'a walk with my best mate or my wife', and listeners can hear his footsteps as he walks along describing the animals in fields around his home (Pictured: William walking with wife Kate Middleton, Duchess of Cambridge)
Although recorded in February, it will air a week after Barbados officially removed the Queen as their head of state.
Patrick Jephson, Princess Diana's former private secretary, described William's candid monologue as a 'revolutionary' moment, adding: 'Far from being woke psychobabble, it's an honourable formula for a successful future reign.'
Palace aides say it was William's idea to take part in the Time To Walk series after hearing previous episodes. Other guests have included country singer Dolly Parton, model Naomi Campbell and boxer Anthony Joshua.
For the episode, Apple has made a six-figure donation to three charities chosen by William: Shout in the UK, Crisis Text Line in the US and Lifeline in Australia.
All offer confidential mental health support helplines. The British charity runs a free text service on 85258.
The series is designed to encourage users of Apple Watches to get outside and walk while listening. At the Duke's request, this episode will be made available for free online to everyone without the need for a subscription.
Parents of boy whose accident is believed to have triggered Prince William's mental trauma praise Duke for his extraordinary 'love and support'
By Abul Taher for the Mail on Sunday
The parents of a boy whose ordeal is believed to have triggered Prince William's mental trauma have spoken of the extraordinary 'love and support' that the future King has given them.
Bobby Hughes was five when he was knocked down by a learner driver while playing with friends outside his house in Saffron Walden, Essex, in March 2017. The driver had accidentally pressed the accelerator instead of the brake when she saw Bobby on the road.
William, who was part of the air ambulance team that raced to the scene, movingly recalls being confronted by Bobby's 'hysterical parents' and how he was affected by the experience.
His crew worked on the youngster – who suffered brain damage and other serious injuries – before William, whose eldest son Prince George was three at the time, helped fly him to hospital.
Weeks later, still dwelling on the accident, William was hit by a sense of despair. 'I felt like the whole world was dying,' he recalls.
He kept in touch with Bobby, now ten, and his family, telling his parents: 'Anything I can ever do for you, don't hesitate to ask me, for Bobby's rehabilitation.'
ORDEAL: Bobby Hughes (pictured) was five when he was knocked down by a learner driver while playing with friends outside his house in Saffron Walden, Essex, in March 2017
Paying tribute to William, Bobby's mother, Carly Hughes, 40, told The Mail on Sunday: 'I think he's amazing, a credit to our country. I can't sing his praises enough.
'I've looked into his eyes and, genuinely, he has got a kind heart. He's a lovely man, amazing. I would be proud to call him my King one day.'
On the eve of Prince Harry's wedding in May 2018, William even found the time to entertain Bobby, Carly and her husband Jeff, 44, at the headquarters of the East Anglian Air Ambulance in Cambridge. Mrs Hughes said: 'When we walked into the room he [William] looked so happy. He was laughing and joking and really lovely. He's so down to earth. We didn't feel like we were talking to the future King.'
Three weeks after the accident, William wrote to the Hugheses – who gave up their jobs to care for their son – saying he wanted them to know he was thinking of them.
He wrote: 'As a father, I can understand the pain, but your son is in the best hands, being worked on by fantastic people... I am sure he will get better.'
Recalling the accident, Mrs Hughes said she remembered seeing William at a community hospital where they had rushed Bobby and how the 'shock and distress' registered across his face.
Later the couple were given the grim news that their son had a five per cent chance of survival. A priest gave him the last rites at Addenbrooke's Hospital in Cambridge.
Pictured: Bobby and his parents with Prince William's East Anglian Air Ambulance team
But against all odds he survived and began to recover – even though at one stage doctors advised his parents they should switch off his life support machine.
Mrs Hughes said: 'I was not a religious person until then, but my faith kept me strong, I prayed daily at the hospital chapel.'
She recalled that when Bobby regained consciousness, all he could do was move his eyes, but gradually, movement started returning to his body.
Bobby will have one more major operation to fit plates on his skull, after which he may only need minor procedures and therapy.
Mrs Hughes said: 'All I now want is for Bobby to grow up, get married and have children. I still want him to lead the normal life he was supposed to lead.'
At the request of Mr and Mrs Hughes, The Mail on Sunday is making a donation to East Anglian Air Ambulance.
'I kept asking myself: Why am I so sad?' With unprecedented candour, mental health campaigner Prince William reveals how the stresses of life as a rescue pilot sparked an episode of dark despair
By Kate Mansey for the Mail on Sunday
When Prince William's air ambulance team was scrambled in March 2017, the details given to the team were scant.
The crew was expecting a minor injury case, but within moments of landing they were fighting to save the life of a little boy left seriously injured after being hit by a car.
While William is careful in his podcast not to identify the child, the parents of Bobby Hughes, who was five at the time of the incident, last night told The Mail on Sunday that they believe it involved their brave boy.
In his most powerful intervention to date in the debate over mental health provision, William reveals how the shock of Bobby's case remained with him and, weeks later, sent him into a state of deep distress.
'I went to this one job. And it wasn't very far,' he says. 'The maximum we flew was 15 minutes. And that was the great thing – you get the aircraft out as quick as you can. It was a short distance.
'I still remember the crew who were on, great mates of mine. We had a paramedic and a doctor on and another pilot flying with me. And the call we get is very brief, not very detailed. So we were expecting a minor injury case.
While William is careful in his podcast not to identify the child, the parents of Bobby Hughes, who was five at the time of the incident, last night told The Mail on Sunday that they believe it involved their brave boy. Pictured: William's appearance on Time to Walk
'Immediately it became clear that this young person was in serious difficulty, sadly been hit by a car. And, of course, there are some things in life you don't really want to see.
'And all we cared about at the time was fixing this boy. And the parents are very hysterical, as you can imagine, screaming, wailing, not knowing what to do, you know, and in real agony themselves. And that lives with you.
'But our team got to work, and they stabilised the boy, and then it was a case of getting him out of there and into hospital. It all happened very fast. And we had the patient there in under an hour. It gives the patient the best chance of survival.
'I went home that night pretty upset but not noticeably. I wasn't in tears, but inside I felt something had changed.
'I felt a sort of, a real tension inside of me. And then, the next day, going back in again to work, you know, different crew. On to the next job.
'And that's the thing, you're not always all together.
'So then you can't spend a day processing it.
'And so, you sort of have a reluctance to talk about it because you don't want to hold each other up. You, you don't want to, you know, burden other people. You also don't want to think, 'Oh, is it just me? Am I the only one who's really affected by that?'
It was some time later that the emotional impact of Bobby's ordeal sent William into a state of mental anguish. 'It really hit me weeks later,' he recalls.
It was some time later that the emotional impact of Bobby's ordeal sent William into a state of mental anguish. 'It really hit me weeks later,' he recalls. Pictured: Bobby Hughes and his parents
'It was like someone had put a key in a lock and opened it without me giving permission to do that.
'I felt like the whole world was dying. It's an extraordinary feeling. You just feel everyone's in pain, everyone's suffering.
'And that's not me. I've never felt that before. My personal life and everything was absolutely fine.
'I was happy at home and happy at work, but I kept looking at myself, going, 'Why am I feeling like this? Why do I feel so sad?'
'And I started to realise that, actually, you're taking home people's trauma, people's sadness, and it's affecting you. But I can't explain why I had that realisation what was going on because a lot of people don't have that realisation.
'And that is where you can slip unnoticed into the next problem.
'I think, until you've been through it, it's hard to understand.
'I was lucky enough that I had someone to talk to at work in the Air Ambulance because mental health where I was working was very important.
'Talking about those jobs definitely helped, sharing them with the team, and ultimately, in one case, meeting the family and the patient involved who made a recovery, albeit not a full recovery, but made a recovery.
'That definitely helped.'
William attended the scene during his time as a pilot for the East Anglian Air Ambulance service between March 2015 and July 2017. Four years after rushing to Bobby's aid, William says he is marked by memories of the day.
'It even makes me quite emotional now,' he says. 'When they come in and say thank you, and, 'Here he is. He's OK.' It's… you know, it still even affects me now.
'But I think, as a human being, when you see someone in such dire circumstances, basically at death's door, you can't help but be affected by that.'
His very personal experience puts his recent work – to raise awareness of the mental health of emergency service workers – into context.
His very personal experience puts his recent work – to raise awareness of the mental health of emergency service workers – into context. Pictured: William in a photo used for the Time to Walk campaign
During an event at Kensington Palace last month, the Duke said that he had found cases involving children much harder to cope with since becoming a father.
His eldest child, Prince George, was three when Bobby was injured.
Speaking to emergency care assistant Chloe Taylor and paramedic Will Parish at the event, William said: 'In the air ambulance, any job I went to with children, that really affected me, much more than I think if I hadn't had children actually.
'So, for me, it was the relationship with my personal life with essentially the family or the incident I was at – I found that very difficult.
'There were a number of times when I had to take myself away because I was just getting too involved in it and feeling it.
'And then I'd go to talk to someone else after the event, which was really important, but it continues, it doesn't really leave you there – you just manage it better.'
'I could talk for hours about flying': How helicopter flights with his father inspired a four-year-old Prince William to become a rescue pilot
William's love of flying was forged during his childhood when he took flights in helicopters, including with his father.
The Prince, who flew with the RAF and East Anglia Air Ambulance, recalls keeping a treasured photograph of one such trip on his bedroom wall.
'I could talk for hours about flying,' he says. 'As a young boy, I went and did a couple of trips, which I was very lucky to have with my father in a Wessex, a very, very old helicopter, no longer flies. And I got to sit in the front.
'I didn't realise at the time how much of an impression it would make on me, but I absolutely adored it. They gave me a photograph from the trip. I had it on my wall, and I kept looking at it, and it kept calling to me like it was saying, 'Come on, what's the next step?' '
William's love of flying was forged during his childhood when he took flights in helicopters, including with his father. Pictured: Prince William aged four in a helicopter cockpit
The next step, it transpired, was to join the RAF in January 2009 after a period in the Army with the Household Cavalry. After graduating as a pilot, he became a search a rescue pilot at RAF Valley on Anglesey in North Wales.
'The moment I started the helicopter training, I realised that it was better than anything,' he says. 'It was one of those things that I just instantly took to and thought, 'This is really cool'.'
The Duke began a new job as a pilot with the East Anglian Air Ambulance in 2015. Speaking on the first day in the job – which he left in 2017 to take up full-time royal duties – he said: 'For me it is also really important to be grounded. I feel doing a job like this really helps with grounding the core of what I am trying to become.'
Like his son, Prince Charles served in the RAF, flying himself to pilot training school in 1971. Three years later, he qualified as a helicopter pilot.
Pictured: Prince William doing his first shift with the East Anglian Air Ambulance in 2015
Mum, Harry and I belted out Simply The Best in the car to fight back-to-school anxiety
By Kate Mansey for the Mail on Sunday
For any passing motorist, it would have been quite a sight. There was Princess Diana driving down the motorway, music blaring from the stereo, singing at the top of her voice with her two sons energetically joining in from the back seats.
Moreover, the Royal pop group had an unlikely additional member – their Royal personal protection officer.
The scene, as Princes William and Harry were being driven back to school by their mother, is vividly recreated by the Duke of Cambridge in what is an affectionate reflection about his mother.
The song of choice, rather aptly, was Tina Turner's Simply the Best and it was deployed by Diana to raise the spirits of her children as they returned to boarding school.
William, 39, admits the happy memories are tinged with sadness as the 'family moment' is cut short as the school gates appear into view and he realises he must say goodbye.
'When I was younger, Harry and I, we were at boarding school,' says William, who began boarding at Ludgrove school in Berkshire when he was eight.
The scene, as Princes William and Harry were being driven back to school by their mother, is vividly recreated by the Duke of Cambridge in what is an affectionate reflection about his mother. The song of choice, rather aptly, was Tina Turner's Simply the Best and it was deployed by Diana to raise the spirits of her children as they returned to boarding school. (Pictured: Prince William with his mother Princess Diana in the back of the car)
'And my mother used to play all sorts of songs to while away the anxiety of going back to school. And one of the songs I massively remember and has stuck with me all this time, and I still, to this day, still quite enjoy secretly, is Tina Turner's The Best [sic] because sitting in the back seat, singing away, it felt like a real family moment.
'And my mother, she'd be driving along, singing at the top of her voice. And we'd even get the policeman in the car, he'd be occasionally singing along, as well.
'You'd be singing and listening to the music right the way out into the gates of school, when they dropped you off.
'And, and that's when reality kind of sunk in that you really were going back to school because before that, you're lost in songs. You'll want to play it again just to keep that family moment going.
'And when I listen to it now, it takes me back to those car rides and brings back lots of memories of my mother.'
Last night, Ken Wharfe, a former Royal personal protection officer told The Mail on Sunday that he was the singing policeman mentioned by William.
Mr Wharfe, 73, who now sings bass-baritone in the English Chamber Choir, said: 'They were such happy times. Yes, there were all the issues of the Royal marriage, but the Prince and Princess did their very best at that time to keep their children out of it, so they were largely oblivious and they had great fun with their mother.
Prince William, brother Prince Harry and mother Princess Diana (pictured together), would sing their hearts out to help the boys' back-to-school anxiety
'The Princess loved Tina Turner and would put the CD on full blast in the car, sometimes in the green Jaguar XJS she had, or other cars, the CD always came with us.
'She played Simply the Best all the time and some Cliff Richard.'
Elsewhere in the Time To Walk podcast, William pays tribute to his mother by referring to the life lessons that she instilled in him. From an early age, she took him and Harry on private visits to homeless shelters.
William has continued the work, taking over from her as Patron of the charity Centrepoint.
'My mother took me to a homeless shelter to meet people who were down on their luck and who had a very difficult time in life,' he says.
'She wanted to make sure that I understood that life happens very much outside of palace walls, and this is what's going on. This is the real world here. And we sat there, and we listened.'
First love Jecca's dad made him a conservationist
By Kate Mansey for the Mail on Sunday
The Duke of Cambridge speaks with deep affection about the father of Jecca Craig, widely considered to have been William's first love.
He met Ian Craig when he and Prince Harry visited the family's 55,000-acre Lewa Downs conservation ranch in the foothills of Mount Kenya in 1995.
He fell for Ms Craig when he returned to Kenya during a gap year after Eton, but they drifted apart before he went to St Andrews University, where he met his future wife, Kate Middleton.
'I had such an amazing experience, where I got to see [Ian] darting an elephant for research purposes, and I must have been 16, 17, something like that,' he recalls.
The Duke of Cambridge speaks with deep affection about the father of Jecca Craig (pictured), widely considered to have been William's first love
'Touching an elephant, seeing it lying there in front of you breathing very slowly, its enormous ribs going up and down, and picking the trunk up and listening to the breathing coming out of [it] in your ear – it's a really special, very privileged experience. And that, for any young guy, is like: 'Wow, this is cool'.'
He continues: 'Back then, conservation was very much a case of: put wildlife over here, put people over there. Don't let them meet.
'And Ian came along with a pretty radical idea, which was: 'You can't keep these two entities separate. They need to be together.' This is where I started to realise what the job is.
'A large part of it was community engagement, getting to meet people and understand their challenges.'
Like William, mother-of-two Ms Craig is a conservationist and helped to found Panthera, which campaigns to save wild cats, and Stop Ivory, which seeks to protect elephants.
Bagpipes? I start my day rocking to AC/DC
His grandmother famously wakes to the sound of bagpipes, and now Prince William reveals that his favourite morning music also owes something to Scotland.
He says the Cambridges start their working week by playing Thunderstruck, a track by AC/DC, the Australian rock band formed by Scottish-born brothers Angus and Malcolm Young.
Prince William reveals that his favourite morning music also owes something to Scotland - as he loves to blast a bit of AC/DC (Pictured: Angus Young of AC/DC)
'There's nothing better, when you're a bit bleary-eyed after the weekend and trying to get yourself back into the grind of the week, than listening to Thunderstruck,' he says of a track that reached No13 in the UK charts in 1990.
The Prince adds: 'It absolutely wakes you up, puts your week in the best mood possible, and you feel like you can take on anything and anyone… It's a difficult song not to dance to or to nod along to.'
Prince William 'had the giggles many times' during Christmas Day church service at Sandringham as he struggled to 'keep a straight face' with his cousins sat opposite him
By Kate Mansey for the Mail on Sunday
It is an occasion intended to demonstrate family unity and the Queen's position as Supreme Governor of the Church of England, but Prince William reveals that the Christmas Day church service at Sandringham has not always been as sober as the public might imagine.
Beginning his walk at the 16th Century building, he says: 'So we're right outside St Mary Magdalene Church. The flag's up and I'm right beside the door we normally go in as a family.
'And what's very good about it is that we sit opposite each other as a family and, growing up, having my cousins sat opposite me has always been quite difficult to keep a straight face at times.
Prince William revealed he has gotten the giggles 'many times' during the Sandringham Christmas Day church service. He took his children for the first time in 2019 (pictured)
The Duke of Cambridge attended his first Sandringham Christmas Day church service in 1987, aged five. He is pictured at the Sandringham service with his cousin Zara Phillips in 1988
'I have had the giggles many, many times in the service. Luckily, no one's filming it. So you can get away with it, and on Christmas Day it's fun to have a giggle and enjoy yourself.'
William attended his first Sandringham Christmas Day church service in 1987, aged five, and took his eldest two children, Prince George and Princess Charlotte, for the first time in 2019.
As well as banks of photographers and TV crews, large crowds are drawn by the lure of so many members of the Royal Family all together.
Looking ahead to the first Christmas without Prince Philip, William speaks fondly of his grandfather, who died in April, aged 99.
William says: 'My family spend their Christmases in Norfolk at Sandringham, in the UK. You've got big pine trees that are quite synonymous with this part of Norfolk. And I love the smell of pine in the winter. It's very soothing.
'As we're walking along here, it's been a walk that my family have done for many, many years on Christmas Day.
'I have strong memories of walking down here, and my grandfather, he used to walk so fast that there'd be huge gaps and spaces between all of us, and there'd be us at the back with little legs trying to keep up.'
'The kids dance in the kitchen to Shakira's Waka Waka... there's lots of hip movement': Prince William gives intimate insight into family life at Anmer Hall complete with bickering children and scenes of chaos
By Kate Mansey for the Mail on Sunday
Prince William has provided an intimate and touching description of family life complete with bickering children and scenes of chaos in the kitchen.
Although the Cambridges live in Anmer Hall, a 19th Century Georgian country house given to them by the Queen as a wedding present in 2011, the scenes of domestic chaos will be familiar to millions who will one day be his subjects.
William recorded the Time To Walk podcast in February when Britain was in lockdown and he, the Duchess of Cambridge and their three children – Prince George, eight, Princess Charlotte, six, and three-year-old Prince Louis – were spending much of their time at their Norfolk retreat.
During the episode, he says: 'What I've been amazed by is how much my children already have inherited my family's love of music.
Prince William (pictured with children Prince George, 8, Princess Charlotte, 6, and Prince Louis, 3) has provided an intimate description of his family life in the Time To Walk podcast
'Most mornings there's a massive fight between Charlotte and George as to what song is played. And I have to, now, basically prioritise that one day someone does this one, and another day it's someone else's turn.
'So, George gets his go, then Charlotte gets her go. Such is the clamour for the music. One of the songs that the children are loving at the moment is Shakira, Waka Waka.
'There's a lot of hip movements... There's a lot of dressing up. Charlotte, particularly, is running around the kitchen in her dresses and ballet stuff and everything.
'She goes completely crazy, with Louis following her around trying to do the same thing. It's a really happy moment where the children just enjoy dancing, messing around, and singing.'
William may find it easier than most to get tickets to a Shakira concert if his children so wish – the Colombian pop star is a member of his Earthshot Prize Council.
'Shakira was my number one person on the list,' he joked during the interview about the new global prize for the environment.
'We tried to get people who genuinely cared for the environment, but were also influences around the world and Shakira has been brilliant at highlighting the plight of the oceans.'
William is alone as he walks around the Sandringham estate during the podcast – but his children are never far from his mind.
Although the Cambridges live in Anmer Hall (pictured), a 19th Century Georgian country house given to them by the Queen, the scenes of domestic chaos will be familiar to millions
Prince William revealed Princess Charlotte and Prince Louis love dancing to Shakira's (pictured) song Waka Waka during lockdown, while his daughter also loves dressing up
'We've got hares running across the field over there, fat English partridges going over the hedge just here with a nice orange tractor up ahead,' he says.
'Louis is obsessed by tractors. It just feels very wild and very, very peaceful.' Tractors have, it seems, been a source of fascination to both William's sons.
In the 2019 ITV documentary Prince Charles: Inside The Duchy Of Cornwall, the Duke of Cambridge was seen inspecting farm machinery, including tractors, and said: 'I should have brought George today; he would be absolutely loving this… He's obsessed.'
Then, on a trip to Wales early last year, he recounted a recent trip to the countryside with his children.
'We've been lambing with the children this week,' he said. 'Charlotte wasn't sure at first, but George was straight in there. Louis loves the tractors.'
William's walk ends at Anmer Hall. 'We're finally here… We spend as much time as we can here. It's very special, it's very peaceful. And we feel very, very lucky to be out in the countryside,' he says.
'We've got the sheep in the fields. We've got the pond here with the duck and the geese on. It's a fantastic place to be.'
Signing off at the end of the 38-minute programme, William references his wife Kate, about whom he is known to be fiercely protective.
'It's been really nice to get out and have a walk,' he says. 'I feel like I've shared a lot of feelings. Feels like I've been on a walk with a best mate, or my wife.
'I'll be heading back inside now, going to see what the children have been up to before I, hopefully, put them to bed exhausted.'
Prince William says Taylor Swift led him on stage 'like a puppy' as he cringes while recalling surprise Livin' on a Prayer performance with US singer and Jon Bon Jovi
By Kate Mansey for the Mail on Sunday
Prince William admits that he obeyed 'like a puppy' when glamorous pop star Taylor Swift ordered him on stage for an impromptu performance with Jon Bon Jovi.
Recalling a fundraising gala in November 2013 for the homeless charity Centrepoint, a cause first championed by his late mother Princess Diana, the 39-year-old chuckles and says: 'I can't believe I'm actually telling you this story… I turn up and Jon Bon Jovi and Taylor Swift are at the event, which nearly knocked me off my feet.
'And then, I went inside, met everybody, a lot of handshaking to do those nights, a lot of chatting. I try and be charming and interactive.
'Occasionally, you're not having a good day, and it's a little harder to come by.
'When I sat down to watch Jon Bon Jovi do his performance, I thought, "That's it. My job is done. I'll get a dinner in a minute, and I might be able to have a chat to some people, and, you know, I'm off-duty a little bit now." '
But matters did not go according to that plan.
'Little did I think what was going to happen next,' he adds. 'I'm sat next to Taylor Swift.
'She's on my left – and after Jon does his first song, there's a pause and she turns to me.
Taylor Swift, Jon Bon Jovi and Prince William, Duke of Cambridge sing on stage at the Centrepoint Gala Dinner at Kensington Palace on November 26, 2013 in London
'She puts her hand on my arm, looks me in the eye and says, "Come on, William. Let's go and sing."
'To this day, I still do not know what came over me. Honestly, even now I'm cringing at what happened next, and I don't understand why I gave in.
'But, frankly, if Taylor Swift looks you in the eye, touches your arm and says, "Come with me…" I got up like a puppy and went, "Yeah, OK, that seems like a great idea. I'll follow you."
'I walked up on stage in a trance and then sort of halfway through Jon Bon Jovi's Livin' On A Prayer song, I wake up.
'And I'm thinking to myself, "Am I standing on the stage singing Livin' On A Prayer when I don't even know the words?"
'But the Centrepoint young guys and girls were there, all loving it and cheering away.
'So I thought, "Well, if they're enjoying it, then the night is for them. So sod it. I can't be the doofus who's going to ruin it for everyone."
'And so I desperately try and remember some of the words and sing as hard as I can.
'Beneath my black tie, there was a lot of sweating going on. I felt like a swan, where I was trying to keep myself composed on the outside, but inside, the little legs are paddling fast.
'Now, a lot of people might think I'm comfortable on stage. When I do speeches and things like that, I've done so many now, they're not a problem. But I've not done singing.'
William's appearance on stage –just four months after he had become a father for the first time – drew comparisons to the event in 1978 when Prince Charles celebrated his 30th birthday by dancing on stage with The Three Degrees.
STAR QUALITY: William and Miss Swift after their number at the Centrepoint gala in 2013
But it quickly becomes clear that, far from parading his association with the world of celebrity, William has a more serious point.
'At times, when you're taken out of your comfort zone, you've got to roll with it,' he says.
'And I think we've got to the stage in this life where we do micromanage ourselves.
'We do worry about: how do we look on social media?
'Who said what about me? What am I wearing? There's so many pressures, but I think that making a fool of yourself is OK.
'It's OK to not take yourself too seriously and have those moments where you let go and you just go, "Do you know what? I'm OK with this." '
While William, who has been Patron of Centrepoint since 2005, may wince at the memory of his performance, Ms Swift, 31, who has sold more than 200 million records worldwide and who is dating English actor Joe Alwyn, has been complimentary.
In an interview with The Mail on Sunday shortly after the event, she said: 'I could hear his voice and it's pretty good. A nice tone. I'd definitely say he has got star quality and if he ever wants me to sing with him again, I'll be there.'
'You appreciate it a lot more': Prince William says he and Harry used to fend off Charles' efforts to cajole them into the great outdoors - but now shares his father's love for the countryside
By Kate Mansey for the Mail on Sunday
Like many children, William says he and his brother Prince Harry tried to fend off their father's efforts to cajole them into the great outdoors – but that he now shares Prince Charles's appreciation of the countryside.
'When I grew up, my father used to love his walking, and still to this day loves his walking and used to try to force Harry and me out of the house,' he says.
'And we weren't really having any of it.
'Now, as you get older, you appreciate it a lot more.'
But William hasn't abandoned all his youthful habits – he likes a lie-in.
Prince William (R) and his father Prince Charles walk through a field on Home Farm in Gloucestershire, Western England, May 29, 2004
'I'm not an early riser, if I can help it,' he admits.
'I quite like watching nature put itself to bed in the evening and the sounds and smells that come with it.
'It's quite therapeutic.
'It stimulates all your senses, and so you really feel like you're in a calmer space, that you can process stuff and think, and I come home feeling better and feeling more relaxed.'