The hard-as-nails punching pensioner who fought off an armed robber at Sainsbury's has been unmasked as a granddad-of-three and ex bus driver who "has never had a fight in his life".

Trevor Weston, 77, from Cardiff, has caused a splash online as his courageous act of self-defence was caught on CCTV for all the world to see.

An armed mugger threatened to stab him if he did not give up his money at the cash point - but Trevor was having none of it, throwing well-time punches and seeing the scumbag criminal off.

Amazingly, Trevor did all this despite recently breaking his right shoulder - meaning he effectively fought the cowardly crook off with just his left hand.

WalesOnline spoke to the granddad-of-three, who said he never had to get violent in all his years on the buses.

Trevor Weston from Tremorfa is a viral star

But for some reason, on Monday at the supermarket on Colchester Avenue in Cardiff, as he was pushed against a bin with a weapon waved in his face, his instincts told him to put up his guard and fight back.

Trevor said: "I'm up at 4am every morning - the result of working on the buses for 37 years, I'm afraid," said Somerset-born Trevor, who has lived in Cardiff since he was a small boy.

"I needed money to buy the papers so decided to drive down to the local Sainsbury's because all the shops closer to me charge you to make withdrawals from their cash machines.

His well-timed punches sent the cowardly crook fleeing

"Normally there's staff milling about outside, waiting to be let in. But, that day, there was no one.

"Anyway, I got out my £20 and had just put my wallet back in my pocket when this bloke - this 'thing' - came from nowhere, grabbed me and said, 'give me your money or I'll stab you'."

Trevor has gone viral as the video clip, captured by a Sainsbury's security camera and shared on social media by South Wales Police, has been viewed almost 40,000 times, with many people praising the pensioner for standing up for himself in a situation where most would have folded and fled.

You wouldn't want to mess with Trevor
Trevor spent a career on the buses

Trevor had made an early morning stop at the store to get money for his daily newspapers when he was approached from behind by a man wearing a hi-vis jacket and a baseball cap.

The would-be robber assaulted him and demanded he hand over his wallet.

But Trevor's skillful blows saw the coward flee in terror.

"I've never had a fight in my life, even when I was dealing with troublemakers on the buses years ago," he said.

"If anyone got on who was drunk, aggressive and refusing to pay, I'd go, 'just go and sit down, mate' - it wasn't worth the hassle.

"But, in this instance, when he demanded I hand over my money, I replied, 'you what? Do you want some of this, pal?' And I put up my guard.

He wasn't flustered by the incident and instead got on with his day

"Actually, it's a good job there's no sound on that video because I probably turned the air blue with what I really said."

Trevor said he had previously broken his right shoulder in a fall at home after putting up some curtains and so could only land a decent left punch on his assailant.

"I cracked him a couple of times and he looked stunned, like he couldn't believe what I was doing.

This is the moment the 77-year-old was caught on camera fighting off the scumbag demanding his cash and bank card
He was ready to fight to protect himself

"And, to be honest, neither could I."

The moment Trevor lands a blow hard on the jaw happened just as the CCTV footage cut out. But Trevor explained this is what finally caused him to stagger away down a nearby public footpath.

"After he'd gone I just drove home and gave my son a lift to work. It wasn't until about 10am that I called the police," he said.

"Also, I only realised afterwards that the bloke had been holding a pencil, not a knife.

The mugger assaulted him but he gave better than he got
It's one to the jaw for this bungling robber

"The officers who came to my house afterwards said he still could have done some damage with it though. They said at one point in the video he had it held against my neck."

Trevor said he has since been taken aback by the amount of people who have wished him well.

"To be honest, I'm surprised how calm I've been about it all. I've been expecting the adrenaline to kick in at some stage and for my hands to start shaking, but no, nothing.

"I've been getting lots of texts, as well as mentions on Twitter and Facebook apparently, but I leave all that internet stuff to my granddaughter."

And did he get a good look at his attacker?

"Not really, he had something pulled up over his face, but he was a young, white bloke with a Cardiff accent.

"I know that because I clearly heard him say 'Oww!' at one point after I'd smacked him," Trevor said.

If you recognise the person who tried to rob Trevor, please call police on 101 or visit Crimestoppers Wales  @Wales_CS quoting reference 043939.