Matt Hancock was involved in a bitter behind-the-scenes clash with then-education secretary Sir Gavin Williamson over moves to keep schools open during the Covid pandemic, according to the latest tranche of leaked messages published by The Daily Telegraph.

The paper highlighted an exchange between Mr Hancock, the then-health secretary, and one of his aides from December 2020 after Sir Gavin persuaded Boris Johnson that schools in England should reopen as planned at the start of the January term.

He said they needed to fight a “rear-guard action” to prevent a “policy car crash” when children returned to the classrooms and started spreading the disease.

The tranche of more than 100,000 WhatsAapp messages was passed to the paper by the journalist Isabel Oakeshott, who was given the material by Mr Hancock when they were working together on a book about his time in government during the pandemic.

Earlier, Ms Oakeshott confirmed that she had broken an non-disclosure agreement with Mr Hancock – although she argued that her action was overwhelmingly in the “public interest”.

However, she acknowledged that he was not happy at what she had done.

“I received a somewhat menacing message from him at 1.20 in the morning,” she told TalkTV’s Piers Morgan Uncensored.

“I think he is extremely troubled about how to respond to this, but this is not about him.”

The latest messages feature an exchange between Mr Hancock and Emma Dean, a special adviser, during a Zoom meeting in which Sir Gavin convinced the prime minister the January reopening should go ahead despite concerns about the second Covid wave then gripping the country.

Ms Dean said the education secretary was “freaking out”, adding: “You can tell he isn’t being wholly rationale. Just by his body language.”

What a bunch of absolute arses the teaching unions are

Mr Hancock replied: “I’m having to turn the volume down.”

At the end of the meeting, Mr Hancock said: “I want to find a way, Gavin having won the day, of actually preventing a policy car crash when the kids spread the disease in January. And for that we must now fight a rear-guard action.”

The Telegraph said the messages show he then contacted Dan Rosenfield, Mr Johnson’s chief of staff, to begin his attempt to have schools closed before children returned, providing him with his private email address.

In the event, on January 4, after many younger children had returned to classes for a single day, Mr Johnson announced schools would close and exams would be cancelled amid a national lockdown. They did not reopen until March 8.

In an article for The Telegraph, Sir Gavin said that he had considered quitting over the decision as he was so unhappy.

“Looking back now, I wonder whether I should have resigned at that point. I certainly thought long and deeply over whether I should have gone then. I just felt so personally upset about it,” he wrote.

The messages also show how Mr Hancock and Sir Gavin had earlier expressed their exasperation with the teaching unions.

Mr Hancock messaged Sir Gavin to congratulate him on a decision to delay A-level exams for a few weeks.

“Cracking announcement today. What a bunch of absolute arses the teaching unions are,” he wrote.

Sir Gavin responded: “I know they really really do just hate work.”

Following their publication by The Telegraph, the former education secretary tweeted that his comments had been “about some unions and not teachers”.

He added: “I have the utmost respect for teachers who work tirelessly to support students.”

A spokesman for Mr Hancock said: “Tonight’s revelations are exactly like last night’s. These are partial accounts, obviously spun with an agenda.

“They show Matt was focused throughout on saving lives. The right place for a full assessment is the (official Covid) inquiry.”