David Cameron is "not very Conservative", according to the actress and family friend Helena Bonham Carter.

Bonham Carter, who has known David and Samantha Cameron for more than 15 years, told the Sunday Times that "he's not that Conservative, actually".

"I mean, he’s not a right-wing person. If he was in America, he’d be a Democrat" she added.

Cameron, she said, also had a "hilarious sense of humour, which nobody really knows about". She said she was "amazed" when he became prime minister, quickly adding that she meant it "not in a bad way".

Bonham Carter later contacted the Sunday TImes to express concern that she "landed my friend Dave in the shit through careless use of words".

She told the paper: "I worried about 'He’s not very conservative' being slung back at him like a boomerang from some back bench."

Bonham Carter is an unlikely friend of the Camerons. Her great-grandfather was the Liberal prime minister Herbert Asquith, while her cousin Jane Bonham Carter is a Liberal Democrat peer.