Robert Jenrick has defected to Nigel Farage’s Reform UK after being sacked from the Conservative shadow cabinet, calling his former party “rotten” and urging more MPs to jump ship.

Jenrick, who stood for the Tory leadership against Kemi Badenoch, said the Conservative party in Westminster “isn’t sorry, it doesn’t get it, it hasn’t changed, it won’t change, it can’t change” before launching into a broadside against his former colleagues, including Mel Stride and Priti Patel.

“In opposition, it is easy to paper over these cracks, but the divisions and delusions are still there,” he said at a hastily reorganised press conference with Farage in Westminster on Thursday. “I can’t in good conscience stick with a party that has failed so badly.”

The former shadow justice secretary had the Conservative whip removed and his party membership suspended earlier in the day, after Badenoch said she had found “irrefutable evidence” that he was planning to defect.

His sacking appeared to have caught both him and Farage off guard. The Reform UK leader called it the “latest Christmas present I’ve ever had” and said it was still “60-40” if Jenrick would defect until Badenoch forced his hand.

As Farage announced Jenrick’s defection, there was a lengthy delay before the former shadow minister arrived on stage, while the Reform UK leader wondered aloud if Jenrick had changed his mind. But he arrived on stage with a denunciation of his former party and its time in government. “What’s the truth? Both Labour and the Conservatives broke Britain. Both parties are committed to a set of ideas that have failed Britain.”

Westminster sources said Badenoch had been monitoring Jenrick’s activities for some time because of suspicions he was working to undermine the party, and she believed his defection to Reform was imminent. A draft resignation speech was discovered and sent to one of Badenoch’s team, parts of which were released by the Conservative party on Thursday.

Speaking to journalists on a visit to Edinburgh ahead of May’s Holyrood elections, where polls suggest the Scottish party will incur heavy losses at the hands of Reform, Badenoch denied this was “a very bad day”. She said that defections to Reform were evidence that “a lot of people who have gone into politics for the wrong reasons”.

“People who go into politics because they think it’s a gravy train, or because they think it’s a way to get on TV, are finding out that the Conservative party is not the party for them,” she said. “And they’re going to the party that is for people like that.”

“Robert Jenrick is not my problem any more. He’s Nigel Farage’s problem now.”

The Tory leader said more details on the “irrefutable evidence” that prompted her to sack Jenrick on Thursday morning would come “in due course”.

“Every time we have a press conference, we have announcements, we have ideas of how to improve the country,” Badenoch said. “When Reform has press conferences, it’s just: here’s another defection.”

Farage had said earlier in the day that there was no imminent defection planned, though there had been conversations with the former Tory leadership candidate.

Badenoch told Sky News that Jenrick was planning to “torch the Conservative party by putting out comments and allegations that would have been very, very bad”.

Shortly before the news broke on Thursday, Jenrick posted on X: “It’s time for the truth.”