Helena Bonham Carter and Dominic West play with fire as Taylor and Burton

Burton and Taylor charts the relationship between two of the 20th century’s greatest screen icons when they meet again on stage, having been married and divorced twice. Private Lives was a perfect piece of casting – a comedy about a divorced couple who end up in adjoining rooms in a French hotel while honeymooning with their new spouses. But the 1983 production, which ran for nine months on Broadway, Los Angeles and in London’s West End, was a car crash, panned by the critics on both sides of the Atlantic. Liz Taylor was drinking heavily and although Burton was on the wagon, he was not a well man and died the following year at the age of 58.

The question at the heart of the film is why they undertook such a long, gruelling stage tour when they were so unwell. The press assumed it was for the money. They were getting $70,000 a week, which was a huge sum. But screenwriter William Ivory has another theory. “They didn’t need the cash. Richard Burton knew the tour would probably kill him and he knew Liz was bad for him but he was an addict. He couldn’t keep away from her. He couldn’t help himself.”

Although the chemistry remained, Burton and Taylor never did get back together. Burton met his last wife, Sally, around that time and married her while on tour, sending Taylor into a fury that exploded nightly on stage. They started inventing lines particularly during the fight scenes. Burton would scream abuse like “Slattern, vermin and fishwife”, while she appeared to take pleasure in hitting him even when it wasn’t in the stage directions. “They were very competitive with each other anyway,” says Dominic West, “but after he got married, Liz would deliberately try and throw him. She even walked on stage with her pet parrot Alvin to see how he would react.”

These days Alcoholics Anonymous would call them co-dependents. Taylor could drink Burton under the table. He admired her for it. She spent the entire Private Lives tour trying to get him to have a drink. He wouldn’t give in, which drove her mad. They were two people who lived life to extremes. “He was easily bored,” says Ivory, “and Liz could never bore him.”

West says playing Richard Burton was intimidating: “It’s the voice. You have to get it right. The film opens with Burton quoting from King Lear, a role he always wanted to play but never managed and the stage direction on the script is ‘Burton has the most beautiful mellifluous voice you’ve ever heard’, which put the fear of God into me.” “No pressure then,” says Bonham Carter, arching an eyebrow. West: “Well, when I drank and smoked all night, it worked pretty well but I didn’t have the stamina to keep it up.”

Both actors say the real revelation of the script was just how funny and sassy Liz Taylor was in real life. She had a bad press from British critics who thought she had led Richard Burton astray. West says Burton was constantly asked by British journalists whether he felt he had sold out to Hollywood and that it hurt him terribly. Orson Welles once said, “Richard Burton had a great talent. He’s ruined his great gifts. He’s become a joke with a celebrity wife. Now he just works for money, does the worst s***.”

Helena Bonham Carter relates one particular TV interview she’s seen where Liz Taylor leapt to Burton’s defence. “She said, ‘Shut up, he just did Hamlet, for God’s sake.’ She was like a huge Rottweiler when people tried to put him down and she was right. There is far too much snobbery about stage versus film. They’re different mediums and she was a great screen actress.”

It’s clear that they both did huge amounts of preparation for the roles, meeting people who knew the couple and reading biographies. Bonham Carter even consulted an astrologer to find out more about Liz Taylor, who died in 2011. “She was really insightful. She told me Elizabeth was a water person. Water is sexual and sensual and that’s the place she operated from.”

West is smirking throughout this revelation. Did he visit the astrologer as well? “Helena gave me the number but somehow I never got around to it.” Instead, he immersed himself in Richard Burton’s recently published diaries and recounts a wonderful story about him and Liz Taylor going to a fair near their holiday home in Mexico. “She volunteered to be strapped to a wheel and have knives thrown at her. She was quite a woman,” he says admiringly. “And she had a big appetite for life,” adds Bonham Carter. “She was a good eater. Unlike actresses these days, she liked her food”.

Both look fascinated when I tell them how I met Richard Burton when I was 17, having been at school with his and Liz Taylor’s adopted child, Maria. He took us for a ride in his Rolls-Royce followed by tea at the Dorchester. I remember him watching me admiringly as I stuffed yet another cream puff into my mouth, saying, “I like to see a girl with a healthy appetite,” before quizzing me about what books I liked. I remember him as warm, kind and down to earth, not at all like the aloof superstar I’d imagined he’d be.

“Was he wearing a brown polo neck jumper?” asks West, “That’s what they put me in for the entire shoot. I’d like to think he was better dressed.” Sadly, I can’t remember what Burton was wearing. I was so overwhelmed by getting a ride in a Rolls and having tea at the Dorchester with one of the greatest celebrities of the day.

In the film, West and Bonham Carter bear an extraordinary resemblance to the couple. They both had to wear blue contact lenses. Bonham Carter proudly gets out her phone to show me a close-up of her with Taylor’s famous violet eyes. William Ivory says the whole production hinged on getting her and West together: “We had to get actors of sufficient stature to play Burton and Taylor and these two have that star quality.”

So how do you follow a role like that? Helena Bonham Carter is off to play a spy in a David Hare film and Dominic West will be portraying a gay activist during the miners strike in a film called Pride. When he says it’s another wonderful script, she asks if there is a part for her.

“If you’re prepared to play a Welsh miner’s wife or lesbian, I’ll have a word,” replies West. He then says he’s worried because he’ll have to lose loads of weight for the role as his character was the second person in Britain to be diagnosed with Aids. “The problem is I am walking to the South Pole after that and I really need a spare tyre for the journey.”

“You crazy man,” shrieks Bonham Carter: “Tell him he’s crazy.”

When I ask West whether he thinks it’s wise for him to walk to the South Pole – even for charity – given that he and his wife Catherine are expecting their fourth baby, he says, “I always get terrible postnatal depression so I thought I should get away for a bit.”

At this point Helena Bonham Carter’s mobile starts vibrating on the table. “It’s Tim” she says referring to her husband, the film director Tim Burton and then says, “Hi honey, I’m just doing an interview,” in her Liz Taylor voice. When he hangs up soon after she quips rather naughtily that her husband “never takes very long”. Our time is also up, but I’m left wanting more of this particular double act.

Burton and Taylor is on tonight 9pm, BBC4