John and Zoe's My Family giggle fit

John Barrowman has revealed he and Zoe Wanamaker got in trouble on the set of My Family because they couldn't stop laughing.

Torchwood star John has a guest role in the 100th episode of the BBC One sitcom, which also stars Robert Lindsay, as a dashing American medic who comes to the rescue of Zoe's character Susan.

"Zoe Wanamaker and I had a really good time, in fact we were both a bit naughty on set - I can't tell you what (we joked about) but you'll watch it and you'll see the giggles in our eyes," he said.

John continued to say they had to pinch themselves to stop laughing before cameras rolled.

"You just think of the lines you're supposed to say, that's it, give yourself a pinch," he said.