Samantha Cameron warned her children to expect to be taunted with "oink, oink" noises from schoolmates in the week after the publication of the "Piggate" allegations against her husband, a radio presenter has claimed.

Comedian Jason Manford said the Prime Minister's wife opened up on how she dealt with the claims when they were filming a celebrity edition of Great British Sport Relief Bake Off.

The show was filmed about a week after the publication of Call Me Dave, by Lord Ashcroft and Isabel Oakeshott, which included unsubstantiated claims that Mr Cameron took part as a student in a bizarre initiation rite involving a pig's head.

Mr Cameron later said that "a very specific denial" had been issued about the claim and that most readers would be able to "see through" the motives of former Tory donor Lord Ashcroft, who admitted he decided to write the book after not being offered a senior government job.

Speaking on his Absolute Radio show, Manford said he was impressed by Mrs Cameron when he met her: "I must say, you probably can guess from my accent that I didn't vote for her husband, but I'm surprised they don't roll her out more. She's just lovely, dead nice, dead chatty. I thought 'She's really nice'."

He added: "It was the week after - what shall we call it? - #PigGate. It was after that had happened. Now I don't think it's true, I don't think it happened. I sort of brought it up. I thought 'I'm just going to mention it'.

"I think at the time for the family it was 'What a ridiculous thing - that's not even a thing'. I guess it was quite humorous, I think, until it went crazy.

"She did say something to me which really endeared her more to me. I said: 'Has it been all right this week at home?' Quite a weird conversation to be having with the Prime Minister's wife.

"I said 'Has it been all right at home, and stuff.' And she said 'Yeah, you know, I just said to the kids Monday morning 'You might get a few oink oink noises at school but just try not to fight with anybody'.

"I thought 'That is good parenting advice, that. That's good parenting'."