Until last year, Hugh Whitemore had only once collaborated with another writer. It was for a long-forgotten BBC venture, The Eleventh Hour, in which two writers were paired on a Monday and their freshly written play broadcast live the following Saturday. Whitemore was paired with Brian Clark. "We thought it was brilliant," Whitemore recalls. "When we watched it, it was unspeakably bad."
This time, at least, Whitemore's co-production has been in gestation rather longer. On the down side, his writing partner will not be around to see it. Simon Gray, a lifelong martyr to nicotine, knew he was dying when he was asked to dramatise his memoirs, The Smoking Diaries. "This was when the cancer had taken a bit of a hold on him," Whitemore says. "And he said, 'I really haven't got the energy. Why don't you do it?' I was immensely moved and flattered, and I said, 'That would be utterly wrong, but we could do it together.'"
Whitemore suggested putting three Simon Grays on stage, one of them to be played by a woman ("to give music and variety"). This was less a steal from the two Alan Bennetts in The Lady in the Van, which Whitemore had never seen, than a riff on Tom Stoppard's idea that playwriting "is the only job where you can talk to yourself and get paid for it".
But Gray, his friend since the early 1980s, was unconvinced. "We had a rather morose dinner," Whitemore recalls, "and he said, 'I don't think it'll work.' I said, 'I'll write a very rough, quick first draft,' which I did. I gave it to Simon, who rang back immediately and said, 'It works!'"
That was at the beginning of last year. Over the following months, Whitemore would walk every day to Gray's home in Holland Park, west London, to work on the play for a couple of hours - usually in the afternoon, since Gray slept in the mornings. "At first, we'd sit around and be rather polite: 'Might I just say one thing about page 33?'" But normal service resumed after a week. "Because I get up at normal hours, I'd look at what we'd done the day before and type things out, saying, 'I don't like this very much,' and he'd send furious emails back saying, 'What do you mean you don't like it? It's rather good, I thought.'"
It won't surprise readers of The Smoking Diaries and Gray's recent Coda that the jokes are located in morbid places. "Simon said, 'The finding of the tumour: should that be at the end of act one, do you think, or the beginning of act two?' I said, 'Oh, terrific end to act one, surely?' And he said, 'Well, good for bar trade anyway.' Then he'd splutter and laugh and reach for a Silk Cut."
Gray expected to see the play through to production (it opens in Chichester tomorrow). The doctors had given him another 18 months, but in August an aneurysm abruptly finished the cancer's slow work. Whitemore takes solace from the fact that their collaboration lightened those final months. "He became much more lively. I like to think it gave Simon a little bubble of extra vitality."
Whitemore and Gray, both born in 1936, belonged to a coterie of wining, dining west London playwrights that also included Harold Pinter and Ronald Harwood; all four share the same agent. In other circumstances, the play might have found its way to Pinter, who was for many years Gray's director. Did he read it? "Oh yes - 'Damn good play.' Poor old Harold. It's been a bad year. I was bloody glad to see the back of it."
Whitemore does Pinter's growl and Gray's bark with relish, the legacy of his early acting career. "There were two people at Rada when I was there who were absolutely hopeless," he recalls. "One was me, and one was Brian Epstein. We used to sit in a coffee bar off Goodge Street, saying, 'What's going to become of us?'"
He got a job writing continuity scripts and progressed into television drama during the genre's golden age; he wrote his first play when he was 40. If, as seems likely, The Last Cigarette fetches up in the West End, it will arrive at the same time as a revival of Whitemore's most successful play, Pack of Lies, about the upheaval suffered by a suburban couple when MI5 tells them their neighbours are eastern bloc spies.
Meanwhile, the BBC will this year screen Whitemore's followup to The Gathering Storm, his award-winning 2002 account of Churchill's wilderness years. Into the Storm finds Churchill looking back on his wartime performance while the electorate ponders his fate in the 1945 hustings. For this least autobiographical of writers, the two films are more personal than they appear. "Although one writes these things about real people, really they're about yourself," Whitemore says. "When they first asked me, I thought, 'I can't do this, I know nothing about Churchill.' But I was then the same age as the Churchill I was writing about. I'm not short, but I am overweight. I like cantankerous argument. I have a tall wife who is very patient with me. I thought, 'Ah, it's really about me.'"
The Last Cigarette, by contrast, bears not a trace of Whitemore. Gray died with the play all but finished, leaving his partner to write on without imposing his own voice on the play. "I'm a good forger," Whitemore says of his ability to disguise his own lines. "You get a major prize if you find them" ·
The Last Cigarette opens at the Minerva Theatre, Chichester (01243 781312), tomorrow. A celebration of the life and work of Simon Gray, featuring Felicity Kendall, Michael Gambon and Simon Callow, is at the Comedy Theatre, London SW1 (0870 060 6637), on Sunday.