Sir Jacob Rees-Mogg has said Tory MPs who defect to Reform UK should hold by-elections, warning their refusal to give constituents a say is undermining Nigel Farage’s attacks on the Labour Party. 

The surprising intervention came after Suella Braverman became the fourth Conservative MP to cross the floor, and said it was not necessary to give her constituents a say on the move.

Speaking on Times Radio this morning, the Tory grandee and ally of Ms Braverman said voters must be given a say, warning that refusing to do so is backfiring on Mr Farage’s party.

Sir Jacob said: “People who change parties should stand in a by-election… I’ve argued for some time that if you change Prime Minister, their mandate is personal for the Prime Minister as people vote for a party and a party leader, and a new Prime Minister ought to have a new general election.

“I think this applies even more strongly to somebody who changes from one party to another.

“I also think it’s very strange that Reform doesn’t see this as an advantage for it, because I fear that they would win all these by-elections and probably win them quite healthily.”

He warned: “It undermines their argument against Labour’s cancellation of the local elections, when they’re not willing to put converts up for election for their own voters in by-elections.”

Speaking at a press conference at Reform HQ yesterday, Ms Braverman said her defection did not warrant a by-election.

The former Home Secretary argued: “I believe in by-elections, definitely, and if I were leaving the Labour Party to go to the Conservatives, or government to go to opposition, I believe there’s a very strong case there for a by-election.

“But as you heard I spent the last general election apologising for being a Conservative, and I believe I won that seat despite the Conservative rosette not because of it.”

While only four defecting MPs have ever held by-elections to confirm their decision with local voters, two of them were when Tory MPs defected to UKIP in 2014, with Mr Farage hailing the decision to give their constituents a say.

The MPs – Douglas Carswell and Mark Reckless – both won their by-elections despite heavy efforts by the Tories.

While the Tories and Labour have criticised Reform UK for refusing to hold said by-elections for Ms Braverman, Robert Jenrick, Andrew Rosindell and Danny Kruger, neither party held by-elections when they received defectors in the last parliament.

A number of high-profile MRP polls have suggested Reform UK would win Ms Braverman’s Waterlooville constituency.