"I have my eye on Mrs Boyle next," quips Tony Boncza. "I just need a director who thinks Agatha Christie would have loved the idea."

Currently on his third male lead, Tony has done the rounds where The Mousetrap is concerned.

He first starred in the whodunit 25 years ago as the elusive Sergeant Trotter, returned to the classic with a stint as Mr Paravicini in South East Asia in 2012 and is currently capping it off with his swan song in the last leg of a nationwide tour as Major Metcalf - barring any future offers on the Mrs Boyle front.

"It's a bit weird," he chuckles. "I know the play very well now. It's so well-crated; that's why it's been running for 64 years and people keep coming back to it.""

His insider track into half the character list would surely have given him license to order the cast about, butt in with pearls of wisdoms or elbow them aside to demonstrate how it's truly done. But Tony, whose extensive CV boasts a host of stage and film roles, including an appearance in Steven Spielberg's Empire of the Sun, is no bossyboots.

"I only give them advice if they ask, 'What did you do there?' or 'Did you find this happened when you did it?" he insists. "It needs to come from them. It's their character, their creation, not mine."

But, he concedes, you tackle fresh parts in an all-too-familiar show at your own risk. He has had to resist the urge to jump in others' place - out of sheer muscle memory.

"It's confusing to begin with. You remember other characters' lines better than your own. Sometimes you might want to come in on their cue."

Po-faced Major Metcalf is a world away from his previous incarnations as the affected Mr Paravacini and unreadable sleuth Sergeant Trotter.

"He is ex-army, old school, and I play him as an homage to old-fashioned black and white comedy films. He's a bit of a buffoon, a kind of a colonel blimp," he chuckles.

Listening to the consummate actor delve into the complexity of his new dramatis personae, it is almost inconceivable he ever wished to do anything else. And yet, as an impressionable teen, all he dreamed off was to be a Fleet Street hack.

This was not to be however. On his first day at the Surrey Comet, he made it as far as a coffee bar in Euston before thinking better of the whole idea.

"I never turned up that day," he laughs heartily. "I did the NCTJ course in Harlow and got my [journalism] diploma but by that time I had joined the National Youth Theatre and that's where my heart lay. I parted company with journalism at that time."

Although he concedes journalists "can be theatrical" the similarities end there. Given his track-record trawling the mean streets of the capital for leads - and utter lack of interest peddling scoops to the tabloids - he has a sneaking suspicion he would not have survived long as a newshound.

"I was there when the Houses of Parliament were blown up by the IRA in 1974. We were driving through and I took a lot of photographs - which I didn't sell to the West End papers. But they did go in our NCTJ newspaper. Even then I wasn't really thinking as a journalist. That's probably why I wouldn't have made it."