The two of us

Since his death (from a gastrointestinal haemorrhage) in January 1995, Peter Cook has been the subject of numerous books and documentaries. But no post- humorous tribute has attracted quite so much interest as the latest drama by Terry Johnson, which will be broadcast this Christmas on Channel 4.

Terry Johnson is a master of what might best be called the post-modern popular history play. Granted, you generally have to wait until you're dead before you can enjoy this dramatic privilege - but when Johnson writes a play about you, you know you really have arrived. Johnson's subjects have ranged from Alfred Hitchcock to Salvador Dali, and it's a sign of Cook's iconic status that his life has been dramatised by a writer whose characters have included Albert Einstein, Sigmund Freud and Marilyn Monroe.

Not Only But Always charts the course of Cook's life from the 1950s to the 1990s, but its backbone is his creative yet quarrelsome partnership with Dudley Moore. Cook wrote and performed much of his finest (and funniest) work with Moore, and even though Cook did most of the writing, Moore provided a unique catalyst for his strange and savage wordplay. Cook was an inspired comedian before he met Moore, and he remained an inspiring comic after they parted. Yet his comedy never flowed so thick or fast as it did when they were together. Far more than a mere muse or foil, Moore's cuddlesome clowning was the perfect complement to Cook's remote and ruthless intellect. Not for nothing was one of Cook's most memorable bon mots that comic non sequitur, "Tragically, I was an only twin."

Tragically I was an Only Twin eventually became the title of a collection of Peter Cook's writing, which I compiled a couple of years ago. I subsequently edited a collection of his work with Dudley Moore - called Goodbye Again, after their ITV series of the same name. I never met Cook or Moore, but even on the printed page, the difference between Cook's solo and collaborative work was immediately apparent. On his own, Cook was brilliant but distant. Moore gave his humour the one thing it lacked - the human touch. After working on these two books, Moore felt familiar but Cook remained a riddle. Which is why, having seen Not Only But Always, I was so keen to meet Terry Johnson. By turning Cook's life into a sort of fiction, had he unlocked a greater truth about Cook that had hitherto remained hidden? Despite its artistic licence (or perhaps, in part, because of it) does his drama reveal more about its elusive subject than workaday journalism will allow?

Johnson has always been fascinated by comedians. His previous plays include Dead Funny, about Benny Hill, and Cleo, Camping, Emmanuelle and Dick, about the Carry On crew. He was inspired to write about Cook (and Moore) by Harry Thompson's biography ("One of the best biogs I've read, really, and biogs are my main reading"). Johnson directed the film himself, on location in New Zealand, though you'd never know from watching it. With apparent ease, he has recreated London, Cambridge and Edinburgh on the other side of the planet. But how easy was it recreating Peter Cook and Dudley Moore?

"It is a film primarily about Peter," says Johnson. "I was trying to do Peter from graduation to dead and that's a long time, so Dudley's story was never going to be as complex." But although Cook remains centre stage, his relationship with Moore dominates Johnson's drama. "I've always known I wanted to write about the aggression that creates good comedy in a double act," he says. And in Cook and Moore he found the ideal duo. The pair created some of the most hilarious sketches of the last century, and the story of how they created them is awash with dramatic incident. Like all the greatest double acts, their partnership was a sort of marriage, and like a lot of marriages, the enduring love between them was punctuated by plenty of private and public ups and downs.

Cook met Moore in 1960, when they were cast alongside Alan Bennett and Jonathan Miller in a new revue called Beyond the Fringe. Their backgrounds and their circumstances could scarcely have been less alike. The son of an electrician, Moore went to Dagenham County High School and won an organ scholarship to Oxford University, despite the handicap of a club foot. When Beyond the Fringe came calling, he was working as a jazz pianist. The son of a diplomat, Cook was educated at Radley, one of Britain's top public schools, and while still a Cambridge undergraduate, he was already moonlighting as a professional sketch writer, writing the largest slice of Kenneth Williams' West End revue.

Cook also wrote the largest slice of Beyond the Fringe - about two thirds, by Moore's estimate, with Bennett and Miller writing the other third between them. Moore's written contribution was chiefly confined to some sublime melodic parodies (Colonel Bogey by Beethoven, Little Miss Muffet by Britten), but his amiable acting hugely enhanced the more cerebral contributions of the other three. As Miller told the BBC after Cook's death, "It's very hard to imagine the success of the show without Dudley's talent as a performer."

In comedic terms, Alan, Jonathan, Peter and Dudley was a combination as potent as John, Paul, George and Ringo. As Bernard Levin observed, up until that point, satirical revue had been basically cowardly. It picked on easy targets, and it left its audience alone. Beyond the Fringe poked fun at the things audiences in those days still held dear - the Church, the armed forces and, above all, Her Majesty's Government. In his influential theatre column, Kenneth Tynan described the show as "the moment when English comedy took its first decisive step into the second half of the 20th century."

Beyond the Fringe became the hit of the 1960 Edinburgh Festival, before graduating to the West End and then Broadway. President Kennedy saw the show in New York, the Queen saw it in London, and when her Prime Minister, Harold Macmillan, came along to see what all the fuss was about, Cook interrupted his (unprecedented) parody of the PM to mock Supermac, in character, from the stage. With an empire that included the Establishment Club ("London's first satirical nightclub") and Private Eye, Cook bestrode Soho like a colossus, and Moore (a star in any other firmament) was dwarfed by his precocious triumphs. In a cartoon of the duo, Gerald Scarfe depicted Moore as Cook's glove puppet. What gives their story (and Johnson's film) such bite is that during the next 20 years, they gradually swapped places.

Cook remained the senior partner for most of the 1960s. When Moore was offered his own TV show by the BBC (Moore's inoffensive musicianship was a far safer bet for Aunty Beeb than Cook's surreal social satire), he invited Cook to appear as his guest, and Cook rapidly assumed pole position. Not Only Dudley Moore But Also Peter Cook became Not Only Dudley Moore And Peter Cook and finally Not Only Peter Cook And Dudley Moore.

Literate yet populist, with a Chelsea boot on either side of the class divide, Not Only... But Also... was one of the smartest sketch shows ever televised, and in Pete and Dud - a couple of amateur philosophers in flat caps and flashers' macs - Cook and Moore created a pair of priceless idiots as timeless as Laurel and Hardy's bowler hatted ne'er do wells. Over three BBC series (plus another on ITV), they took an artform that had remained rooted in the pre-war world of music hall, and dragged it, kicking and screaming (with laughter), into the modern age. They transformed the three-minute sketch, much as The Beatles transformed the three-minute pop single. Like Lennon and McCartney, they injected fresh sophistication into a critically neglected genre, and gave a format previously dismissed as a trite amusement a brand new lease of life. For the first time, here was a sketch show that was daft and intellectual, erudite and dangerous. And they were damned sexy, too (racking up seven marriages between them, in the end, as well as countless liaisons along the way). From Monty Python to The Comic Strip, from The Fast Show to The Office, the best British comedy of the last 30 years is inconceivable without them. As Johnson says, "Pete and Dud are one of the major roots of it all."

Sure enough, it wasn't long before the cinema came calling, but like a lot of the best comedians, Cook and Moore's potent chemistry proved hard to capture on the big screen. One of their films, Bedazzled, is now rightly recognised as a cult classic, but it wasn't an outright hit at the time. Their natural home was the stage, and in 1971, they embarked on a new live show which confirmed their stardom on three continents. Behind the Fridge (aka Good Evening) toured Australia, ran for a year in London's West End and another year on Broadway, before setting off on tour around the States. The lighter sketches were as funny as ever, while the darker ones (and there were a fair few of those) bore comparisons with "proper" playwrights like Harold Pinter. Yet Cook had been drinking heavily, and when the show finally closed, in Los Angeles in 1975, Moore (now married to the American actress Tuesday Weld, who was expecting their baby) decided to stay in America and try his luck as an actor. For the best British double act since Morecambe and Wise, it was the beginning of the end.

Cook and Moore did team up for a few more projects thereafter, but they never matched the prodigious magic of their Sixties heyday. Moore made two more LPs with Cook (as Derek and Clive, their X-rated versions of Pete and Dud) but these malevolent albums lacked the warmth of their Derek and Clive debut - a profane but amiable bootleg, recorded purely for their own amusement during the Broadway run of Good Evening. In 1977 they collaborated on one last movie, The Hound of the Baskervilles. With Cook as Sherlock Holmes and Moore as Doctor Watson, it should have been the perfect big screen vehicle for their quintessentially English talents. Sadly, the film was a flop (Barry Took called it one of the worst films ever made) and when Moore got his big Hollywood break, opposite Bo Derek in 10, followed by an even bigger hit opposite Liza Minnelli in Arthur, his partnership with Cook receded into history. "I wasn't surprised," Alan Bennett told Moore's biographer, Barbra Paskin, after Moore's elevation to LA aristocracy. "My only surprise was that they hadn't got onto him sooner."

The rest of Cook's comic career was a mystery wrapped in an enigma - 15 years of languid semi-retirement punctuated by a few superb yet sporadic flurries, such as his comic tour de force on Clive Anderson's talk show and his sombre but absorbing radio series with Chris Morris, aptly entitled Why Bother?. In his last interview, less than two months before he died, he described Not Only... But Also... as the happiest time in his career. "That was perfect," he said. "I can't imagine a comedy relationship being better. I adore Dudley. I would have been very happy for it to continue."

So why didn't it? Well, partly for practical reasons (Moore's American family for one), but for professional and personal reasons, too. On the professional front, Moore rightly sensed that the best outlet for his talents no longer lay in playing Cook's lovable fall guy. On the personal front, being the chief target of Cook's rapier wit for 15 years would surely have worn down anyone's self-esteem, with or without Cook's drinking. Every joke has its victim, and in many of Cook's funniest jokes, that victim was Moore. This sadomasochistic undercurrent gave their partnership its momentum, but eventually it tore it apart. As long as this theatre of cruelty was safely confined to the stage, these ritual humiliations made uncomfortable yet riveting viewing, but Cook's unremitting baiting was bound to affect Moore in the end. Yet there was terrific affection too ("I think they had great trust in each other," says Johnson) and above all a shared sense of fun that, despite the bickering and sniping, is faithfully captured in Johnson's film. "I think they made each other laugh a lot," he says. "They found each other funny - very funny."

In the autumn of his life Cook mellowed, and he managed to repair his friendship (though not his partnership) with Moore. By now, Moore's movie career was in decline, which must have made such a reconciliation easier. "I was tops for around two years," Moore said shortly after Cook died. "And then, one morning, you wake up and find you've been shifted onto another list. You're no longer an A-list actor. You're on the B-list - and falling." Cook knew the feeling. He'd experienced it himself - more than 20 years before.

During the last decade of his life, Moore returned to his first love, classical music, becoming something like the musician he might have been if he'd never been cast in Beyond the Fringe. He died in 2002, aged 66, from pneumonia brought on by progressive supranuclear palsy, a rare syndrome related to Parkinson's disease. Throughout the Eighties, Fleet Street liked to compare Cook's leisurely Hampstead lifestyle with Moore's Hollywood superstardom, but in retrospect their solo careers don't actually look all that different. And although the things they did on their own would have been more than enough for most lifetimes, it's the things they did together which will still be remembered in a hundred years.

So that's Cook and Moore's story - at least, the way I chose to see it. But how does my partial account compare with Johnson's film? Well, as someone who only knew Cook or Moore through their comedy (the only way most of us know them), it certainly encapsulates the personalities of the two men I imagined whenever I saw or heard or read their work. Naturally, there are numerous compressions and omissions (how else do you fit a lifetime into a hundred minutes?), but the essence is all there. Rhys Ifans' Cook is magnetic and enigmatic and Aidan McArdle is a subtle and engaging Moore.

But not everyone who knew Cook has been entirely happy with Johnson's portrait. "This is a Peter I barely recognise," Cook's second wife, Judy Huxtable, said recently. "A feckless, arrogant bully, bitterly jealous of Dudley's commercial success, incapable of emotional commitment and haunted by failure." Huxtable felt that Johnson's film "reduced a man known for his savage wit and brilliant observation to the level of a village idiot."

Viewers who never knew Cook will probably judge the film less harshly, and Johnson is the first to admit that his research was not exhaustive. "I could have spent six months talking to people, and chose not to. That's just the way I do it. I take a handful of facts, a briefcase full of facts, and then I imagine things, and sometimes it's right and sometimes it isn't." Yet you sense that if he'd spent those six months talking to all the people who knew Cook and Moore, he'd probably be a bit further from his own truth, and no nearer anybody else's. "In the end, we have more commonality of experience than we realise," he says. "It's a sleight of hand but an honourable one. It just seems to work.

"It's very difficult when you're doing a life story," says Johnson. "A life is a bit like a Loch Ness monster. It has a lot of arcs. And to dramatise a life, inevitably you only see one or two loops of the monster." Better, perhaps, to anatomise one or two loops, as Johnson does, rather than wrestle with the whole serpent.

In the end, the Cook of this film (and, you suspect, any film) remains as mysterious as ever. True talent is always otherworldly, and there's bound to be something unknowable about someone who had the alchemic knack of making a joke out of almost anything. "I guess in the process of writing someone they usually reveal themselves, or the storytelling is such that you wish them to reveal themselves, and I don't know what it was about this one," says Johnson. "I think our Peter remains as enigmatic as he was."

Johnson works at that weird interface where fact and fiction meet, but any sort of writing (especially journalism) is similarly selective. Any account of any life is bound to be a fictitious compromise - a vast, undulating landscape viewed through a single, subjective lens. We all accept that movies are merely personal responses to the novels that they're based on and as Shakespeare surely knew when he wrote his history plays, it's inevitable that the drama of a human life should be much the same. "You don't know what it's about until you've done it, a lot of the time," says Johnson, for whom the real meaning of this drama only dawned on him when he sat in a crowded cinema, in a sea of strangers, watching it for the first time. "It's about the cost," he says. "It's about what it costs, I think, to be a comic." Cook and Moore endured that cost, which is why their best work was also the most painful. But as Not Only But Always reaffirms, the comedy that came out of it was invaluable, at any price.*

William Cook edited 'Tragically I Was An Only Twin - The Complete Peter Cook', and 'Goodbye Again - The Definitive Peter Cook and Dudley Moore', both published by Century. 'Not Only But Always' will be screened on Channel 4 at 9pm on 30 December