Downing Street has been forced to deny that David Cameron swore in the chamber of the House of Commons during Prime Minister's Questions.
Viewers had to lip-read Mr Cameron after his microphone cut out for a few seconds while he answered a question about the Electoral Commission's report on the Scottish independence referendum from SNP MP Angus Robertson - and some of them concluded he had been caught using very unparliamentary language.
A clip of the comment was soon circulating on the internet, and visitors to the popular political website order-order.com were invited to vote on whether they thought Mr Cameron had told Mr Robertson "Will you f*** off". The site's host, Guido Fawkes, said he personally was "in the no camp" on the question.
Mr Robertson himself played the incident down, sending a message on Twitter: "Didn't hear David Cameron use unparliamentary words in PMQs. Shame he didn't commit to all Electoral Commission recommendations."
Downing Street insisted that Hansard, the official record of parliamentary proceedings, would make clear that Mr Cameron did not swear.
Asked if she could deny that the PM swore, a Number 10 spokeswoman said: "Absolutely. I think he said 'What are you frightened of?'"