Rival David Cameron biographers have locked horns over the veracity of a lurid story about the Prime Minister and a pig.
Isabel Oakeshott, co-author of the Call Me Dave book being serialised in the Daily Mail, said it is for "people to decide for themselves" if the claim the PM was involved in an embarrassing Oxford University club ritual with a pig was true.
But Anthony Seldon, author of Cameron at 10, questioned the "integrity" of the tome, arguing: "Who cares?"
Isabel Oakeshott: "We've left people to decide for themselves if it's true."
Ms Oakeshott, a former Sunday Times political editor, wrote the book with Lord Michael Ashcroft, the former Tory party donor and treasurer who has admitted a "beef" with Mr Cameron over not being offered a top Government job despite underwriting the 2010 election campaign.
Earlier in the day she said the story was included because it was "fun".
In a debate on BBC's Newsnight about the story dubbed #PigGate, Mr Seldon said: "Who cares? I haven't read the book and I haven't read the snippets. But you can't have been alive in England today and not been aware of a lot of stuff going on.
"This man is running the county. It's extremely difficult, he's trying to keep us safe. Terrorism. Big issues in Iraq. Syria. Huge issues over the economy. The future of Europe. Why are we here talking about stories that might well not be true?"
Anthony Seldon: "Who cares?"
Ms Oakeshott defended the section, pointing out it was a few paragraphs in a much bigger work, and said the sole source was a "distinguished MP".
She said on the programme: "What we have said is this is the account we were given. Initially we dismissed it as a joke. The source repeated it on a number of occasions. So we've left people to decide for themselves if it's true.
"It's quite normal to present information and allow people make up their own minds - on the one hand, on the other. Newspapers do that every day."
But Mr Seldon said: "The world integrity is really important here. As authors we have huge responsibility. What we say is often believed even if they are not true."
Ms Oakeshott began to say his "books are very serious academic pieces of work", adding: "You are hugely respected for it."