Asked earlier if Sir Keir had confidence in his deputy, the PM’s official spokesman said: “Yes, the prime minister works closely with the deputy prime minister… on delivering on the public’s priorities.

“There is a court order which restricts her from providing further information, which she’s urgently working on rectifying in the interests of public transparency.”

Sir Keir defended Ms Rayner himself in an interview with BBC 5 Live and said it was a “mistake” for people to brief against her or talk her down. He said: “Angela is deputy prime minister of this country, that’s an incredible achievement.

“And Angela came from a very humble background, battled all sorts of challenges along the way, and there she is proudly — and I’m proud of her — as our deputy prime minister. Angela has had people briefing against her and talking her down over and over again. It’s a mistake, by the way.”

The PM then mistakenly called Ms Rayner, who is often talked up as a replacement for Sir Keir, the prime minister. He said: “Angela is an incredible prime minister — deputy prime minister — but what a great story of British success that we are a country where Angela Rayner could be our deputy prime minister.

“I’m proud of that. I think we should be proud as a country that Angela Rayner is our deputy prime minister, and that, by the way, will give I don’t know how many working-class children, particularly girls, a real sense of aspiration.”

A spokesman for Ms Rayner said: “The deputy prime minister paid the relevant duty owing on the purchase of the Hove property in line with relevant requirements and entirely properly, any suggestion otherwise is entirely without basis.”