THE EU 27 will play “hardball” with the UK during the forthcoming negotiations to leave the bloc, the UK’s former ambassador to Brussels warned MPs yesterday as he told them not to expect any new trade deal before 2022 at the earliest.

Sir Ivan Rogers, who resigned in January complaining of the Conservative government’s “ill-founded arguments and muddled thinking”, said leaving without an agreement – as the Prime Minister has suggested – would be catastrophic.

Rogers also told the Commons Brexit select committee the EU was determined to keep trade talks separate from the Article 50 divorce agreement, and suggested it could take until this summer “even to agree on what the negotiations should be about”.

He was pessimistic about whether German Chancellor Angela Merkel or other EU leaders would allow any separate deals for sectors such as the car industry, as Theresa May has said she wants.

“The unity of the 27 will win out and I think [Merkel] and others will agree there will be no sectoral deals in either the single market or the customs union,” he said, adding that he expected this to appear in the EU negotiating mandate.

Rogers said there seemed little prospect of negotiating a trade deal alongside the exit talks, as May has also said she would like, predicting the question of the UK’s exit bill and continuing contributions would be key.

“The key players, the key officials, the key technocrats, the key theologians” in the EU think a new relationship may not be agreed until 2022 even if negotiations proceed “unprecedentedly fast”, he said. And before any deal “the budgetary issue will come to the fore”.

The question of Britain’s exit bill and budget contributions during any interim deal would come to a head at a “gory” summit in autumn 2018, he said.

“I think we can expect a number of them to think, if the British want a future trade deal, and some form of transitional arrangement before a future trade deal... it will come together with the money equation,” Rogers said.

“And there will be some who will want to play hardball and say: ‘Well, absent British money over a transitional period, why the hell should we give them any trade deal?’”

Rogers said he expected “quite ferocious” legal disputes over the size of the UK’s exit bill and what exactly it is based on. Reports have suggested the EU will ask for a divorce settlement of up to €60 billion before opening exit talks.

But he said it would nonetheless be disastrous for the UK to leave the EU without agreement on a trade deal.

A “cliff-edge” Brexit would be “insane” and damaging economically for both the EU and Britain, he said – but could happen.

Meanwhile, a report yesterday issued a warning that Brexit fears could lead to waves of British expats returning from the continent and put increased pressure on UK infrastructure.

Researchers believe thousands of over-65s, fearful over their future as UK citizens on the continent, may return to the UK without having property or pensions, increasing pressure on public services like the NHS.