TORY Brexiteer Jacob Rees-Mogg has urged Theresa May to revive her threat to leave the EU without a deal.

The chair of the European Research Group, which represents about 60 of the most pro-Brexit Conservative MPs, suggested in an interview yesterday on BBC One’s The Andrew Marr Show to claim that the UK could be more intransigent because it was in a much stronger negotiating position than people realised.

He gave his views as it emerged the backbencher has bought a £5 million home next to Parliament, fuelling speculation he is positioning himself as the next Tory leader.

The five-storey mansion is even closer to the House of Commons than Downing Street is – and until recently was the political HQ of pro-Tory tycoon and power-broker Lord Ashcroft, a supporter of Rees-Mogg.

Despite being the favourite among Conservative members to be the next party leader, Rees-Mogg said he had no wish to replace May in No 10 – but did not unequivocally rule it out.

He told Marr he was concerned the UK was losing out in the talks because the concessions were “all very one way”. He said he did not want May to walk out of the process but suggested the government should offer an ultimatum.

“We are paying a very large amount of money, £40 billion, and in return we want a trade deal. Everything else is essentially incidental to that,” he said.

“The £40bn is of great importance to the EU because after March next year it still has 21 months of the multiannual financial framework, and it expects that to be funded by the UK. It would have to cancel projects or get more money out of the Germans if it doesn’t get our money.

“Nothing is agreed until everything is agreed. Therefore we should reiterate that and say, quite clearly, if we don’t get the trade deal we want, you don’t get the money. And that’s a very strong negotiating position.”

If the UK were to refuse to pay the so-called Brexit bill, the withdrawal agreement due to be finalised in the autumn would collapse and the UK would leave the EU on 29 March 2019 without any transition period.

In 2017, at the start of the negotiation process, May talked up the possibility of the UK leaving with no deal, saying it would be better than a bad deal.

When pressed, May has tended to repeat the line, but in practice ministers have all but abandoned the notion, largely because there is an acceptance that the short-term impact of a no-deal Brexit on the economy would be disastrous.

Rees-Mogg said he thought May was wrong to state in her Mansion House speech that the UK would not leave Ireland to sort out the border issue on its own.

He claimed that under article 24 of the General Agreement on Tariffs and Trade (Gatt), the UK and Ireland could leave current border arrangements in place provided they said they were working towards a free trade agreement.

The backbencher also dismissed the claim from Jon Thompson, the head of HM Revenue and Customs, that the “maximum facilitation” customs plan favoured by Brexiters could cost British business up to £20bn a year.

Meanwhile, amid the speculation over the future Tory leadership, former party leader Iain Duncan Smith told Sky’s Sophy Ridge on Sunday that anyone plotting to overthrow May should “shut up” and get on with delivering Brexit.

Deputy Labour leader Tom Watson said no decision had yet been made on whether Labour MPs would be whipped to oppose membership of the single market when the Commons votes on the issue in June.

“We haven’t decided our whipping arrangements yet,” he said on ITV’s Peston on Sunday.

“We haven’t made a decision yet, but we’ve been pretty clear that there are deficiencies in the Norway model that might not work for a bespoke UK deal,” he added.