The actor and comedian Dudley Moore has died at his home in New Jersey, a spokesman said this evening. He was 66 years old.
Moore began his career in Beyond the Fringe, a groundbreaking satirical review, and entered into a double act with the comedian Peter Cook before making a successful transfer to Hollywood in such films as 10 and Arthur.
He had been ill for many years with progressive supranuclear palsy and died from pneumonia, a complication stemming from his condition.
In Beyond the Fringe, which played for two years in London and moved to Broadway, Moore teamed with Cook, Alan Bennett, who later became a successful playwright, and Jonathan Miller, now an opera producer and medical doctor.
With Cook the pair became Pete and Dud in the television series Not Only ... but Also, probably best known for the two comics' cloth-capped alter egos who rambled through the meaning of life, and for sketches such as a one-legged actor being turned down for the role of Tarzan.
They also plumbed the depths of taste and decency in a later series of recordings as Derek and Clive, though pirate copies of the tapes - some of which were banned - freely circulated among fans.
Chat show host Michael Parkinson, who interviewed Moore on a number of occasions, paid tribute to "a bloody good comedian and a lovely man".
He said he and Cook were "a great comedy duo" but said Moore also had "a little boy lost quality".
"He was the most charming of men and delightful company, a superb musician, a bloody good comedian and a lovely man."
Film director Michael Winner said Moore's partnership with Cook "changed the whole attitude to comedy" in Britain.
"He was the loveable one of the two, he was the funny one and the sweet one but with immense skill as well.
"He was just a wonderful chap. I shall miss him very much."
Cook and Moore made their screen debuts in The Wrong Box in 1966, and followed up the next year with another success, Bedazzled, that put the devil into late 1960s London.
Moore confessed to being driven by feelings of inferiority about his working class origins in Dagenham, east London, and his small stature at five foot two. In later life he also spoke of the pain of being rejected by his mother because he was born with a deformed left foot.
In the mid-1970s Moore settled in California, where he met the film director Blake Edwards in a therapy group and landed a part in 10 when George Segal walked out of the production.
The 1979 film, co-starring Bo Derek, established Moore as a Hollywood star. Two years later, he had another as Arthur, a rich drunk in the film of same name who falls for Liza Minnelli.
His career waned and in the 1990s he seemed to suffer one illness after another. He underwent open-heart surgery and had a series of strokes.
Moore - who has two sons, one from his second marriage, the other nearly 20 years later from his fourth marriage - was also thought to be appearing in public drunk by outside observers.
In fact he had been suffering the effects of a degenerative brain problem, progressive supranuclear palsy.
By this time his film career had effectively ground to a halt after his peak and he was fired from Barbra Streisand's film The Mirror Has Two Faces because he found he could not remember his lines. Losing the role, he said, was "devastating".
Moore made his condition public in September 1999, pointing out that his vision had become hazy, his walking was impaired and speech slurred.
Moore had even seen his prowess on the piano keyboard slowly slip away.
However, he occasionally found an air of humour even in the darkest of hours, wracked by the disorder.
Announcing his illness in a statement, he said: "I understand that one person in 100,000 suffers from the disease and and I am also aware that there are 100,000 members of my union, the Screen Actors Guild, who are working every day.
"I think, therefore, it is in some way considerate of me that I have taken on the disease for myself, thus protecting the remaining 99,999 members from this fate."
More often, though, he would be realistic about his helplessness. In a TV interview Moore said: "I am trapped in this body, and there is nothing I can do about it."
And in an interview he recorded for BBC1's Omnibus programme, he said: "There's always this feeling of 'why did it hit me?' and I cannot make peace with it because I know I am going to die from it.
"Yes I feel angry, that's true - to be reduced to this insignificant version of myself is overpowering."
