Tom Hollander on playing the last days of Dylan Thomas

Tom Hollander tells Gerard Gilbert how he gorged himself on chocolate to resemble the bloated hell-raiser in his decline

Poetry in motion: Tom Hollander as Dylan Thomas, with co-stars Phoebe Fox and Ewen Bremner, in 'A Poet in New York' (BBC)

It may seem a little strange, as one Dylan Thomas expert has already commented, to be celebrating the 100th anniversary of the birth of Wales's greatest poet with a TV drama about his death. But as Andrew Davies, the writer of BBC2's A Poet in New York, points out: "Death is always a convenient thing. I've always felt as a dramatist that it was a shame that the death penalty was abolished, because that was always a good point to flag back from."

Thomas passed away in New York City at the age of 39, 10 days into a lucrative reading tour of America; the uncertain cause of his death has already spawned several books, including one claiming that he was killed, Michael Jackson-style, by his doctor, and another that he had undiagnosed diabetes. Davies was however keen not become embroiled in a whodunit.

"I didn't want to do a pathologist's view of my favourite poet," says the multi-awarding winning Cardiff-bred dramatist, who was inspired to be a writer after he won a school-recital prize reading Under Milk Wood. "I wanted to celebrate his life and his poetry, and the last few weeks of his life was a good place to flashback to childhood, particularly his love affair with Caitlin, which started off so idyllic and then finished up in this terrible deadlock."

It's a lot to cram into just one hour of relatively low-budget drama, recreating 1953 New York with some inventive production design and the judicious use of back-projection. Those wanting a fuller picture of Thomas's relationship with his wife Caitlin may want to refer back to John Maybury's 2008 film The Edge of Love, starring Matthew Rhys and Sienna Miller as the younger Thomases. In A Poet in New York we get a sadder version of the man, bloated and seriously ill after decades of hell-raising, requiring Tom Hollander to bulk up on chocolate and other sweet goodies. "It's not as fun as it sounds eating as much as you want," he says. "After about 48 hours of it you're full, then you feel sick and have sweats and go to the loo at all sorts of strange times of day. I had to put the weight on very quickly and then take it off very quickly because we were about to start the third series of Rev, and I thought, 'I mustn't get diabetes.'"

Hollander was less concerned about looking right for the part than he was about speaking like Thomas. "There was an initial huge relief on discovering that he didn't sound that Welsh," says the actor, producing his iPhone on which he has stored recordings of Thomas performing his poetry. "Listen... he sounded more like Richard Burton. There's some Welsh music to it, but it's an English voice... This was a time when aspirant Welsh people were losing their Welsh and becoming the Anglo-Welsh."

Hollander and Essie Davis in the drama (BBC)

Practising while driving in his car, Hollander nevertheless had to tone down Thomas's speaking manner. "It now sounds so fruity you wouldn't believe it," he says. "I had to make it sufficiently faithful to his 1940s voice, but not laughable to a modern ear."

By his late thirties, the perennially broke poet was fast becoming a superstar on the other side of the Atlantic. "I had been unaware of Dylan Thomas's extraordinary success in America," says Griff Rhys Jones, whose production company, Modern Television, originally envisaged telling the story as a documentary. "What I hadn't understood was that he had actually written Under Milk Wood to be performed in America, and it got its first performances in America. He was the biggest literary export to America since Dickens."

"He was a Fifties rock star in many ways," agrees Aisling Walsh, the director who had the unenviable task of shooting the drama in just 18 days, including recreating an exterior of the Chelsea Hotel in the Cardiff studio. "He was part of the first generation that makes it to Greenwich Village... it's 1953 so it's before Bob Dylan... it's before any of that. You often wonder what would have happened if he had survived this. Would he have gone to Los Angeles and worked with Stravinsky? Would there have been screenplays for movies?"

Instead, Dylan fell into a coma, dying four days later – officially from pneumonia, although pouring whisky on to an already enlarged liver probably hastened his end. "Someone that famous now would be in the Priory," says Hollander. "He would be strong-armed straight into the VIP room to dry out. Mind you, when Philip Seymour Hoffman died people say, 'It's amazing – surely he couldn't have been neglected that much and died and if he was that famous.'

"I did find it very moving to play someone who couldn't conceive of a future for himself. For me, his best stuff is the stuff he writes about youth, about his boyhood – and he somehow can't imagine himself as an older man, so there's a sort of death wish. Dylan Thomas knows how to be a roaring boy running around but he doesn't know how to be an eminent poet... he can't perform the next level of role for himself. I found that compelling."

Thomas's body was returned to Wales, being buried in the churchyard at Laugharne, the Carmarthenshire town supposed to be model for the fictional community of Llareggub in Under Milk Wood and where he had lived with Caitlin. The flashbacks in A Poet in New York were filmed in Laugharne itself. "Dylan's grand-daughter (35-year-old Hannah Ellis) came on the last day and she was so moved by it," says Hollander. "She had his curly hair which was a very touching thing to see for some reason.

"People in the local pub insisted he wasn't a big drinker, and one of them was so drunk he thought I was Dylan Thomas... that it was still the 1950s. Actually it was a bit of a nightmare."

'A Poet in New York' is on BBC2 at 9pm on Sunday 18 May