Robert Powell uses his little grey cells for his latest role

It was a throwaway line about arguably the greatest role any actor can attempt. There are others that have vexed many a thesp, from the notorious (Hitler) to the iconic (Thatcher) to the beloved (Eric Morecambe). Then there are those fictional characters that are reinvented for successive generations. Think Sherlock Holmes as essayed by Basil Rathbone via Jeremy Brett to Benedict Cumberbatch. There’s no way to do it right but many ways to do it wrong.

Robert Powell is on tour in Black Coffee, Agatha Christie’s 20s murder mystery and the only one to feature her Belgian sleuth Hercule Poirot. Having seen what Albert Finney, Peter Ustinov and David Suchet could do with it, what did Powell think he could bring to the part? “David did a cracking job for 20 years, but it wasn’t a light character, was it?” says Powell without any hint of cattiness. “He wasn’t funny. That’s what Albert and Ustinov brought to it. And that’s what I’m bringing to it. I’m putting the humour back. Poirot is a pompous, self-opinionated, arrogant bloke but he also has a strong twinkle and an ability to flirt quite fiercely with the pretty young ladies that surround him in our show. He uses it. He knows what he’s doing.”

At 70 Powell is just old enough to have been part of the end of the repertory movement in the late 60s and early 70s. Yet Christie never cropped up during his salad days. He’s come to her style and her character late on. Was he a fan of the Poirot stories?

“Nope. Never have been,” he answers blankly. “This has been a complete revelation to me. I read my first Christie book about three months ago when I knew I was going to do this. “But now… I’m not going to say that I’m going to read the rest because it’s not my style. But I completely admit that she’s an infinitely better writer than I thought she was.” There are those that might mutter that Christie’s style is stuck in an era that is neither remembered nor relevant. “But that’s fine,” counters Powell. “That’s part of the glory of it: that makes the play for the audience very entertaining. It’s a period piece; it’s set in 1929. Its great fun, great fun.”

Having fun is key to understanding Robert Powell. When he started out in the mid-60s he had bit parts in Robbery and The Italian Job, played Jude the Obscure, and then became a TV heartthrob in Doomwatch. One TV job sticks in his memory. It was a Wednesday Play called Bam! Pow! Zap! by Nigel Kneale.

“It was a huge part, playing a London thug. I was never off the screen. In those days a Wednesday Play was seen by about 10 million people. I was the Benedict Cumberbatch of my day!” he laughs. When the film roles dried up Powell went back to TV and a long stint in Holby City. When he looks back over the career, playing everyone from Dr Frankenstein to Richard Hannay he’s content with his lot and his legacy.

“When you’re talking about me taking a role, it’s me. It’s always me. It’s always going to be, whatever I do. It’s like following Robert Donat [as Hannay]. It never crossed my mind. Robert Donat is him. Me is me. I will never be like anybody else because I always use very large parts of my own personality when I’m acting. Everybody does. They deny it, but they all do. But I admit: it’s me turned to a couple of degrees, that’s all.”

Black Coffee is at the Grand Opera House, York, March 31-April 5.