New Labour MP Christian Wakeford has said the Prime Minister’s reaction to the investigation into parties held across Whitehall during coronavirus restrictions had only strengthened his feeling that he was right to leave the Conservatives.

The Bury South MP told The House magazine there was no “final straw” that made him decide to leave the Tories, where he had been a member for 18 years.

But that the reactions of some former colleagues to his defection – and the actions of Boris Johnson since – had convinced him he had made the correct choice.

Mr Wakeford caused shock when he crossed the floor minutes before Prime Minister’s Questions and took his place behind Labour leader Sir Keir Starmer last month.

In his interview with The House, he revealed his “number one achievement” on that day was “not throwing up”.

“Considering I was sat behind Keir, I’m sure he’s greatly appreciative of that,” he said.

But his move had not been without criticism, with anonymous briefings and outright attacks from Tory MPs criticising his move.

Scott Benton, the Tory MP for Blackpool South, dubbed Mr Wakeford “Christian Wokeford” in a tweet where he said he was “very disappointed”.

While Culture Secretary Nadine Dorries tweeted Mr Wakeford did not realise that a Union flag face mask he wore in the Commons “is not welcome on that side of the House”.

Mr Wakeford said some Conservatives had asked after him, but he added: “It was unfortunate that it got into quite nasty personal briefings against me. But if the lowest you can get is personal attacks, then actually that just reinforces that it was the right decision.”

In the run-up to his decision, the MP said: “There had obviously been quite a few moments where [the Tories] had been incredibly annoying.

“They were reeling out minister after minister to defend the indefensible. It was unedifying. I was slowly coming to the realisation that the party I had been in for 18 years had changed and I had changed.”

He said little had been done since to give him any inkling he had made the wrong choice.

“Boris Johnson isn’t suitable to be a leader, let alone a Prime Minister,” he said.

“It all just reinforces that the decision I made… was actually the right one.

“For those who’ve written letters but have not submitted them, I say: if not now, when?”

He added: “They owe it to the country and to themselves to actually bring it forward, to make sure that he’s replaced. The longer it goes on, the more damage is caused.”