WHILE you were gorging on chocolate during the Easter Bank Holiday, David Suchet was strictly off treats. He had to watch his waistline for his next role - so he could squeeze into a corset.

The Adver meets the actor, best known as Poirot, days before the start of rehearsals for Oscar Wilde's The Importance Of Being Earnest. And he has decided cinching himself in is the only way to carry himself like Lady Bracknell.

"I will have to wear a corset, otherwise I may find myself doing this," he says, legs akimbo, a deep belly laugh bubbling up. "And that would be unacceptable on every level, especially for the stalls!"

His career began on the stage as a member of the Royal Shakespeare Company in the 1970s and television roles followed, including in 1985 playing Inspector Japp, opposite Peter Ustinov as Poirot in Thirteen At Dinner. Four years later, he would take on Agatha Christie's meticulous Belgian detective himself - a role he played until Curtain: Poirot's Last Case, in 2013.

He admits he's still slightly in mourning for Poirot.

"I'll never let him go. I'll never be able to because he's on our screens all the time somewhere in the world," he says, chuckling.

A few weeks ago, Suchet and his wife Sheila went to Prague for a weekend they had bid for in a silent charity auction - and he saw the extent of Poirot's reach.

"We walk into the hotel and there's these young people behind reception who see me and go bananas because they grew up in the 90s, and with all the problems in Prague, watching Poirot gave them comfort.

"One person had tears in their eyes to say that their mother and father were kept going by the series. You just do the job and go home - but it's had such a wonderful, far-reaching effect beyond just being entertainment, and that's very humbling."

But back to Lady Bracknell, whom he will be playing on stage at the Theatre Royal Bath between Monday, June 15 and Saturday 20 before taking up residence at London's Vaudeville Theatre until November.

"I'll be a woman for six months," he declares, then stops.

"Did I say that? Did I say I'd be a woman for six months? I think I did," he adds, before collapsing in giggles. He's only once before donned a dress to play Napoleon escaping in disguise, but he makes a very attractive woman, from promotional pictures of the new play.

"I never thought I'd be thanking someone for giving me that compliment," he says.

Suchet concedes that he's excited but also "nervous" about taking on such a formidable character.

"She's nouveau riche - she's not naturally born to high society, so it's putting on airs and graces, which is why she's such a great comic character."

And then, of course, there's the "a HANDBAG?!" line - Lady Bracknell's reaction to discovering her prospective son-in-law was adopted after being found in a handbag in Victoria Station.

"I have no idea how I'm going to approach it. In rehearsal, I expect we'll try a hundred different ways and end up not knowing how to... That scene starts and the audience is just waiting for the line, it's just like 'To be or not to be', isn't it?

"You've just got to take a deep breath and get through it as best as possible."

Tickets for The Importance of Being Earnest cost between £24 and £39. They are available at the Theatre Royal Bath Box Office on 01225 448844 and online at www.theatreroyal.org.uk.