And the 33-year-old Scot’s role in the seminal social realism play in the Capital comes hard on the heels of filming a movie which is guaranteed to bust box office records - the latest instalment of the big screen version of Harry Potter.

Tennant will be seen by millions as Barty Crouch Jr, the son of a Ministry of Magic official who has ended up as dark wizard baddie in Harry Potter And The Goblet Of Fire, something the actor is looking forward to tremendously.

"It’s just great," he gushes. "It just such a huge, big thing isn’t it? . . . an enormous rumbling franchise, and it’s nice just to visit that world for a bit."

Tennant, who was brought up in Paisley, has worked with some big names during his career but, given that Harry Potter reads like a veritable who’s who of British acting, was there anyone he was in awe of?

"Not really," he says. "I knew Michael Gambon, Maggie Smith and Alan Rickman anyway, having met them or been in things with them down the years.

"It was actually just really good fun, particularly getting to listen to Michael telling ribald tales for a few days."

The Harry Potter part came about after Tennant starred in a play last year at the National Theatre. Nothing unusual in that you might think - exceptt when you consider that in Martin McDonagh’s The Pillowman, Tennant played the role of a horror writer being interrogated by the police following the violent deaths of several children.

"Mike Newell, the Harry Potter director, came to see the play and then he offered me the part. It was pretty straightforward - though they did have to send a tape to America, seeing as they didn’t know who the heck I was."

So how much of an impact on his future does he feel that appearing in the most sure-fire box-office hit of the year will have? "I wouldn’t actually think it will make much difference to me," he says, playing down his "minor part" in the grander scheme of things.

"Just about everyone outside of the kids are relatively small parts and I’m just one of the British luvvies lined up to do their bit.

"I don’t imagine it will change my life particularly, but I’m just very proud to be a part of it."

And confessing that he doesn’t have any work lined up after Harry Potter, Tennant jokes that his involvement with the boy wizard could spell an end to his career. "This will probably be the last you hear of me now," he jokes.