In an interview with the BBC Radio 4’s The World This Weekend on Sunday, the former prime minister said that what was happening to the “crumbling” NHS was a “national tragedy” and that it was now “very clear” that the Vote Leave promise about Brexit leading to higher NHS spending would not be honoured.

“When the facts change, I think people are entitled to change their mind,” said Blair, who has always been a strong opponent of Brexit but who has rarely been so explicit about being on a personal mission to stop it happening.

Asked if his purpose in relation to Brexit was to reverse it, Blair replied: “Yes, exactly so.”