The image of Henry Cooper putting Cassius Clay - soon to be known as Muhammad Ali - on the canvas remains one of the most enduring memories in British sport.
Cooper's left hook had Clay reeling
It happened on 18 June 1963 and it nearly changed the course of heavyweight history - no one was to know then that Ali would become one of the most recognisable men in the world.
At the time, Clay was considered a loudmouth who was almost certainly going to get his come-uppance when he fought world champion Sonny Liston.
Cooper was British heavyweight champion, regarded as a competent boxer whose major problem was a susceptibility to cuts.
Clay seemed to be in for an easy night when he came to London on a warm summer's night to fight Cooper, a man he had described as a 'bum'.
But in round four, things got very interesting.
"I hit him with a perfect left hook," Sir Henry told this website.
"Unfortunately, the punch landed too late in the round, because the bell went at four or five.
"Ali's trainer Angelo Dundee has openly admitted over the years that he knew he had less than 50 seconds to revive his man.
"So he just stuck his finger into a hole that had appeared in Ali's glove and tore it further apart."
Dundee brought the tear to the attention of the referee who insisted that a new glove be brought out, which translated into a two-minute delay.
By the time the fifth round started, Clay was refreshed and his slashing punches re-opened a cut by Cooper's right eye which forced the fight to be stopped.
Nearly three years after the bout, Cooper got a rematch, although this time, he was fighting the world champion who had also changed his name.
On this occasion, Cooper could do nothing with Ali, who had significantly improved and lost in five rounds again, but the Englishman's place in British boxing folklore was assured.
He became very much a national institution, his views always sought on the state of boxing and his quiet dignity coupled with charity work saw him earn a deserved knighthood.
It's a funny thing. Although I lost the fight, it couldn't have worked out much better for me than it did
Despite his fiercely competitive streak inside the ring, Cooper has never felt any bitterness about the events that denied him a possible victory 40 years ago, as well as a world title shot against Liston.
"It's a funny thing. Although I lost the fight, it couldn't have worked out much better for me than it did.
"Jim Wicks, my manager, never fancied my chances if I fought Liston. He wouldn't have let me fight Sonny, although I would have gone in there and tried to move around the ring.
"I only ever think about it when people remind me. I didn't even realise it was 40 years ago until The Sun's Colin Hart reminded me about it recently.
"Time goes by quickly when you enjoy yourself and I never think if or but.
"Over the years, I've had lunch and dinner with Angelo Dundee and he always admits that he did use a bit of chicanery.
"But professional boxing is a tough old sport. If the boot had been on the other foot - Jim Wicks might have done the same for me."