Actor Chris O’Dowd tells Roz Laws that he might have a long-lost celebrity relative from Birmingham.

Actor Chris O’Dowd would be a good candidate for the genealogy show Who Do You Think You Are?

He recently discovered that, thanks to his philandering great-grandfather, he has a Midlands branch of his family he had no idea existed.

He’d like to track them down – and find out if he really is related to the singer Boy George.

Chris, the star of TV sitcoms The IT Crowd and FM, plus Richard Curtis’s new film out today, was amazed to learn more about his family when he went home to Roscommon in Ireland for Christmas.

He reveals: “I found out that my great-grandfather, a travelling salesman with a wife and family in Cork, had another, illegitimate family in Birmingham.

“My dad thinks that from that family was spawned George O’Dowd, better known as Boy George. It’s not a common name.

“All this only came out after my great-grandfather’s death and is a bit of a family secret, but I’d love to find out more about it.”

Boy George has an aunt, Teresa Gladwin, who lives in Quinton, Birmingham, and he once worked at the city’s Rag Market selling shoes.

The 47-year-old singer is currently serving a 15-month prison sentence for handcuffing a male escort to a wall and beating him.

But Chris says: “He’s still a great bloke. I met him at the Brit Awards a couple of years ago and he said, ‘I presume we must be cousins’. We joked about it, but now it turns out we could be!”

Chris, 29, spent most of last year playing a DJ, in two roles set 40 years apart.

In ITV2’s FM, set in a London radio station, he is bumbling Lindsay Carol alongside Kevin Bishop and Nina Sosanya.

And in the new film The Boat That Rocked, he is breakfast DJ Simon, working on board pirate station Radio Rock, moored in the North Sea in 1966.

The stellar cast includes Philip Seymour Hoffman, Bill Nighy, Emma Thompson, Nick Frost, Rhys Ifans, Jack Davenport and Kenneth Branagh.

Chris says: “To research the role for FM, I watched Chris Moyles and Chris Evans at work, but for The Boat That Rocked I listened to hours of Radio Caroline sets on YouTube. Mainly Tony Blackburn, who was so funny.”

Chris confides that he was unsure about taking the role until Richard Curtis swayed him with a piece of casting news.

It wasn’t the prospect of working with Oscar-winner Seymour Hoffman that did it, but the prospect of getting into bed with a gorgeous woman.

“Richard rang and said, ‘You should know, we’ve cast the most beautiful woman in the world as your wife’. And she is. She’s January Jones, a stunning American actress who’s in Mad Men. I was a bit thrown by her incredible looks when I met her.”

Not that this is a screen marriage with a happy ending. “I’ve cast myself as a loser for quite a while now,” smiles Chris, who is single. “I’m a bit perturbed by how easy that seems to come to me!”

Another memorable part of the shoot was standing on the steps of London’s National Gallery in his underpants, while filming Simon’s stag night.

“It was 6am at the end of a night shoot, when Trafalgar Square was busier than you might think. It was full of commuters and tourists and there were a lot of people photographing me.

“We did it a good few times and it may have gone as far as standing in the fountains.

“I don’t think I’ll ever live it down. And I notice it’s in the trailer!”

Chris is a man in hot demand, as The Boat That Rocked is one of four new films he’s in this year.

He’s now off to Hollywood to make Gulliver’s Travels with Jack Black, playing the Lilliputian baddie, Edward Edwardian. “Edward is engaged to Emily Blunt, but she is stolen from me. I’m always with a beautiful woman but it never works out,” he sighs.

After The Boat That Rocked, Chris will next appear on the big screen in the British sci-fi comedy Frequently Asked Questions About Time Travel.

Later this year sees the release of Hippie Hippie Shake, which co-stars Sienna Miller, Hugh Bonneville and Derek Jacobi, is set in 1960s London and remembers the satirical magazine Oz. It dared to print a cartoon of Rupert Bear considered so obscene it landed those responsible in prison, though they were later acquitted on appeal.

Chris is playing Oz co-editor Felix Dennis, now a millionaire publishing magnate who lives in 730 acres in Dorsington in Warwickshire when he’s not relaxing on the Caribbean island of Mustique.

Chris says: “He’s one of the most charismatic men I’ve met, full of great stories. He was going to chopper me up to his country estate but I was working, unfortunately.”