While there was no official dress code for the occasion, it seems both the Cambridge family and Sir David Attenborough decided blue was the colour for their meeting in the gardens of Kensington Palace on Thursday.
The friendly meeting saw everyone donning something blue - from Princess Charlotte's sporty pumps to Sir David's linen jacket - as they gathered to watch the nature historian's new environmental documentary A Life On Our Planet in the palace's grounds.
The Duchess of Cambridge looked effortlessly chic in a £1,295 Gabriela Hearst denim shirt dress, and seemed to perfectly co-ordinate her family's style to match her own in various shades of blue.
The family showed off their impressive outfit choices in two photographs released by the palace to mark the occasion, with the first showing Sir David as he met with the Duke and Duchess of Cambridge and their three children.
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Kate Middleton has once again matched her children to her fashion choice, with the Cambridge family wearing an array of blue outfits as they met with Sir David Attenborough on Thursday
Dressed in a dapper blue linen jacket and navy strides, the naturalist, who hit headlines recently after joining Instagram and amassing a million followers in just four hours, is seen standing a safe distance from the family who are gathered around a bench in their gardens.
Meanwhile Kate, 38, is seen smiling in her on-trend denim shirt dress and £475 navy Rupert Sanderson pumps. Charlotte, five, meanwhile opted for a slate blue dress, with a pair of sky blue pumps.
Gabriela Hearst is a label famed for their accessories, and has amassed a host of famous fans in the form of the Duchess of Sussex, Anne Hathaway and Oprah Winfrey.
The Duchess of Cambridge's long-sleeved denim dress is Italian-made, 100% cotton and features a shirt style collar, front button closure and adjustable sleeve length.
Check mate! Prince George, seven, was photographed (above) looking intrigued as he handled the fossilised tooth from an extinct Carcharocles megalodon. Like his dad, he sported navy chinos with a blue checked shirt, while little Prince Louis, right, had a similar shirt but with a warm-looking blue polo-shirt style jumper on top.
Kate Middleton managed to perfectly co-ordinate her entire family's attire, with Louis head-to-toe in blue and has once again matched her children to her fashion choice, with the Cambridge family wearing an array of blue outfits as they met with Sir David Attenborough on Thursday
It appears high-street brand Zara could be becoming a favourite of young royal Charlotte, who wore a £23 Zara floral Peter Pan collar dress for the meeting with Sir David and a pair of sky-blue laceless pumps.
Charlotte was seen donning the brand's sold-out houndstooth dress in May, which also featured the shop's distinctive ruffled collar.
Sir David gifted seven-year-old George a fossilised giant shark's tooth to mark their first meeting, after discovering how the young prince was such a fan.
George, in a £40 Trotters checked shirt and £50 Start-Rite school brogues, handled the giant tooth with evident amazement.
William ,38, laughed with the broadcaster wearing a navy jumper underneath his grey blazer while Louis, two, donned a light blue jumper with a pair of navy shorts and matching socks.
Socially distanced in the open air, the Duke of Cambridge and Sir David were offered directors' chairs with their names printed on the back - but in a change of plan they sat in each other's seats (pictured)
While there was no official dress code for the event, even Sir David, 94, joined the colour scheme, wearing a signature blue suit.
Kate recently revealed that her youngsters were 'massive fans' of Sir David, and were disappointed they didn’t get to meet the national treasure during their parents' catch up with him for ITV documentary, Prince William: A Planet For Us All.
William and the veteran broadcaster watched A Life On Our Planet, a revealing and powerful first-hand account in which Sir David reflects on both the defining moments of his life as a naturalist and the devastating changes he has witnessed.
Socially distanced in the open air, the Duke of Cambridge and Sir David were offered directors' chairs with their names printed on the back - but in a change of plan they sat in each other's seats.
High-street brand Zara could be becoming a favourite of young royal Charlotte, who wore a £23 Zara floral Peter Pan collar dress for the meeting with Sir David. Pictured, Charlotte wearing the brand's sold-out houndstooth dress in May
The 94-year-old broadcaster chatted to William, Kate and their three children George, Princess Charlotte and Prince Louis after the screening on Thursday.
William interviewed Sir David at the World Economic Forum in Davos, Switzerland, last year, and during the discussion the broadcaster warned that humanity needed to act so that they did not 'annihilate part of the natural world'.
The Duke and Duchess of Cambridge also previously met the conservationist in September 2019 at Birkenhead, for the naming ceremony of the polar research ship the RRS Sir David Attenborough, with the encounter appearing in the upcoming ITV documentary, Prince William: A Planet For Us All.
The Duke and Duchess of Cambridge also previously met the conservationist in September 2019 at Birkenhead (above), for the naming ceremony of the polar research ship the RRS Sir David Attenborough, with the encounter appearing in the upcoming ITV documentary, Prince William: A Planet For Us All
In a new clip to promote the royal's programme - which shows his passion for the planet and search for ways to restore the environment for the next generation - Prince William is seen greeting the broadcaster by saying: 'Here’s a recognised face,' while Kate admits that George, Charlotte and Louis are disappointed to not be in attendance.
The duchess, who revealed in lockdown that her eldest son was often watching David Attenborough's Blue Planet, says: 'The children were very upset that we were coming to see you and they weren’t coming. They’re massive fans of yours.'
With a shared passion for protecting the natural world, William and Sir David continue to support each other in their mission to tackle some of the biggest environmental challenges the planet faces.