The Scottish Secretary has said he is “optimistic the PM will endure” and will “reset” the Government, as he sought to defend Boris Johnson amid a string of Cabinet resignations.

Alister Jack also said the Prime Minister was “mugged” by a birthday cake at one event during the partygate scandal.

The Prime Minister is in a “robust” mood despite Sajid Javid, Rishi Sunak and other ministers leaving government in the wake of the Chris Pincher affair, Mr Jack said.

He spoke to journalists on Wednesday morning.

Prime Minister’s QuestionsBoris Johnson is under massive pressure after a string of resignations (Stefan Rousseau/PA)

The Scottish Secretary said: “I’m optimistic the Prime Minister will endure.

“The road is bumpy and I’m not going to pretend otherwise. But he’s faced challenges before and he has endured.

“He needs, we need, a reset of the Government and that will come.”

The Scottish Secretary said the Prime Minister had apologised for the handling of the Chris Pincher affair.

On the partygate scandal, he said: “He was mugged, as was Rishi, by a birthday cake they didn’t see coming as they sat in the Cabinet Office.”

He continued: “They didn’t attend a party, a party arrived and caught them out.

“I mean, let’s be honest about that.”

Mr Jack said: “The Metropolitan Police saw the word party after birthday and gave the pair of them a fixed penalty notice. And that is a matter of fact.”

“But on the other questionnaires, numerous questionnaires that he filled in, the Metropolitan Police did not see parties happening.”

He said the Prime Minister was unaware of some Downing Street parties, adding: “I think you have to be fair and say, of the events that were work events that he filled in the questionnaires and sent to the police, the police agree they were work events, and he was not fined.

“And on the one occasion, when someone popped in with a birthday cake, during a day of busy meetings, he did get a fine because the word party comes after birthday.

“So I mean, let’s just put it into some context.”

Asked about the Prime Minister’s mood following the resignations, the Scottish Secretary said: “He was in a robust mood, but he absolutely recognises that, you know, mistakes have been made and as I said he is apologetic.”

He said Rishi Sunak did not come up in his conversation with the Prime Minister.

He added: “He wants to reset this Government and he was in that frame of mind.”