David Cameron is to make an unprecedented apology in person to the Queen after saying she "purred" in pleasure at the Scottish referendum result.
The Prime Minister confessed to being "very embarrassed" and "extremely sorry" over the gaffe, which was caught on camera as he chatted with billionaire media tycoon Michael Bloomberg in New York.
Microphones picked up the Prime Minister revealing how the monarch reacted during their phone conversation on Friday morning.
He told Mr Bloomberg: "The definition of relief is being the Prime Minister of the United Kingdom and ringing the Queen and saying 'It's alright, it's okay'. That was something. She purred down the line."
The conversation took place as Mr Cameron was being accompanied around Mr Bloomberg's offices in front of TV cameras.
The Queen remained publicly impartial during the referendum campaign, but the Prime Minister's comments suggest she was relieved that people living in Scotland voted 55% to 45% in favour of retaining the Union.
Downing Street has already contacted Buckingham Palace to offer the PM's apologies and it is understood that Mr Cameron will say sorry in person when he next meets Her Majesty for one of his regular audiences.
Speaking to reporters in New York, Mr Cameron was asked whether he regretted the comment and whether he would say sorry.
He replied: "Yes and yes."
And he added: "Look, I'm very embarrassed by this. I'm extremely sorry about it.
"It was a private conversation, but clearly a private conversation that I shouldn't have had and won't have again.
"My office has already been in touch with the Palace to make that clear and I will do so as well."