Then he was offered the "extraordinary" role of quintessential quizmaster Chris Tarrant in the upcoming TV drama about the Who Wants To Be A Millionaire? coughing major scandal. And suddenly that resolution was history. It's a bravura performance. He cleverly captures the essence of Tarrant's cheeky charm without ever tipping over into caricature. But not everyone was thrilled with the casting, he tells me. "I was at the Pride Of Britain Awards," recalls Sheen, "just after we'd finished filming. Walking down the red carpet having my photograph taken, I suddenly heard someone behind me speak. 'Nothing like me!' said a voice. I turned to find myself face-to-face with Chris Tarrant.
Quiz begins at 9pm on ITV on April 13 (Image: ITV)
"I'd never met him before so it was a very weird experience to find myself chatting with him. But he was lovely. Very friendly, very warm, very generous."
Quiz, the drama Sheen stars in, is based on what has been described as the most British crime of all time.
In 2001, Charles Ingram, a British Army major, was accused of cheating his way to the £1million jackpot on game show Who Wants To Be A Millionaire? by conspiring with his wife, Diana, and another former contestant seated in the studio audience who, it was alleged, would cough when the correct answer was repeated out loud by Ingram.
Quiz begins on ITV on April 13, adapted from a stage play that ran in Chichester and the West End. But somehow it seems better suited for television. Not only was it directed by the peerless Stephen Frears, but the studio was a precise replica of the original quiz show set. And that realism added an extra edge to the actors' performances.
Says Matthew Macfadyen, giving a spot-on performance as Ingram: "Walking on to the set for the first time was fantastic. No acting was required because you were there under the lights feeling all of that real fear contestants would have felt."
Sian Clifford, best known as Fleabag's sister, Claire, plays Ingram's wife Diana.
"That music is designed to get under your skin," she says, "and it works. It's so easy to watch from your sofa but it's very different when you're there, even though you're acting and it's not real."
People still claim they saw the edition of Millionaire when Charles Ingram was allegedly "coughed" to victory. Not possible, says writer James Graham. "That episode was held back by ITV, because they were already suspicious of the outcome. Elements of it, however, were subsequently included in a documentary." Ingram, his wife and another contestant Tecwen Whittock, were eventually convicted of "procuring a valuable security (the prize money) by deception". But doubt remains over whether they were guilty.
Helen McCrory plays uncompromising defence barrister, Sonia Woodley. "I don't have a particularly vivid memory of the scandal," she says, "because the tragedy of the Twin Towers happened a couple of days later.
"But when I read the scripts, I was quickly gripped by the narrative. What's so clever is that your mind is changing all the time. I ended up with a their big question mark over how culpable the Ingrams were."
The truth can be a slippery concept, she says. "At school, my two children have a lesson all to do with what's fake news and what isn't. Was someone coughing in the audience? Well, certainly, there were coughs throughout but from various audience members. Could Charles