Jacob Rees-Mogg doubles down on claim civil servants are manipulating Brexit figures in heated exchange

“I do think they’re fiddling the figures,” Jacob Rees-Mogg MP told BBC Radio Four’s Today programme, after he was accused of suggesting this in the House of Commons without evidence.

Host Nick Robinson had put it to Rees Mogg that his accusation was “not the behaviour of a man who wishes to lead this country”, adding the “eccentric backbencher” was now being talked about as a future prime minister.

Charles Grant, the think-tank chief to whom Rees-Mogg originally attributed the claim, also criticised Rees-Mogg for not apologising for misquoting him, as Brexit Minister Steve Baker had.

On Today, Grant said Baker showed he was an “honourable man” but added he was “surprised” Rees-Mogg had not also apologised.

On Thursday, Rees-Mogg said Grant, head of think-tank The Centre For European Reform, had told Baker that “officials in the Treasury had deliberately developed a model to show that all options other than staying in the Customs Union were bad and that officials intended to use this to influence policy”.

The minister said this was “essentially correct” but a recording of Grant’s remarks was later released, showing he had not said this.

Robinson asked Rees-Mogg if he would apologise. The MP answered: “The only thing I’ll apologise for is that it turned out to be much more serious than I thought.”

Grant said: “The Treasury’s not trying to undermine the government policy... Once you decide to leave the EU, you can consider various ways of doing it.

“The Treasury cares about economics so is naturally pushing for the sorts of Brexit that minimise the economic damage... Many people the Treasury think we should for go that less damaging option.”

He dismissed Rees-Mogg’s attack on officials for briefing him about Brexit. He added: “Of course everybody in think tanks speaks to govern officials. That’s how think tanks work.”

Robinson said Rees-Mogg was “an amusing backbench eccentric” but was now “the leading figure in terms of backbench Brexiteers and many ministers say you’re a likely candidate to be our next Prime Minister”.