LONDON (AFP) - Former British heavyweight champion Sir Henry Cooper, who famously knocked down Muhammad Ali in 1963, before becoming a cult hero for his lionhearted performances in the ring and modesty out of it, died on Sunday aged 76. He passed away at his son's house at Oxted in Surrey, southern England, just two days short of his 77th birthday. The London-born Cooper met Ali -- then known as Cassius Clay -- at Wembley in 1963, with the British fighter famously flooring the great American. Many fans were convinced Cooper had been robbed of victory by some ringside trickery. Towards the end of the fourth round of that non-title bout, Cooper floored Clay with a trademark left hook known as 'Enry's hammer'. Ali, who later said the punch "not only shook me, it shook my relations in Africa," was saved by the bell and then aided by some quick thinking from trainer Angelo Dundee, who noticed a tear in Ali's gloves that he then opened up and brought to the attention of the referee. In the time it took for new gloves to arrive from the dressing room, Ali recovered and in the next round stopped Cooper. Three years later, with Ali now the world heavyweight champion, the pair met again in London and Cooper's face was a bloodied mess when the fight was halted in the sixth round. Recalling the glove incident from their first bout, Cooper, who won the British, European and Commonwealth titles but never became a world champion, said: "I always say if the boot had been on the other foot Jim (Wicks, Cooper's manager) would have done something like that for me. He (Dundee) noticed the stitching on the right glove had stretched so he just stuck his thumb in and ripped the glove open. They had to send back to the dressing room (to replace it), which was 150 yards away at Wembley, so he had a two-and-a-half-minute interval, which to a fit guy is all you want. I'm not bitter about it at all. It's many years ago now," Cooper insisted in 2007. Cooper, who was the first sportsman to win the BBC Sports Personality of the Year award twice (in 1967 and 1970), retired from the ring in 1971 after a defeat to Joe Bugner. Cooper, who lost his wife and twin brother in recent years, fought 55 times as a professional. Current WBA world heavyweight champion David Haye led the tributes to Cooper. "He's a guy who put Muhammad Ali on the canvas and he's got so much knowledge that he's passed on to so many people," Haye told Sky Sports. "He'd let you know his opinion - whether you wanted to hear it or not - and I believe the advice he's given me over the years is working out because I'm now the heavyweight champion of the world." Britain's WBA light welterweight champion Amir Khan told the BBC: "I met Henry in London a few times. He was very humble, we had a good conversation about my own career and what steps I should be taking. He told me not to rush it as a pro, pick the right fights at the right time. I'm young and there are bigger fights ahead. It was great advice." Former world champion Lennox Lewis tweeted: "R.I.P. Sir Henry Cooper. Former British, Commonwealth and European Champion. My deepest condolences to the Cooper family." England footballer Wayne Rooney also added his tribute. "R.I.P Sir Henry Cooper. One of Britain's all time greats. Gutted, deepest sympathy to his family. Such a sad day."