Theresa May prepares to take control at 10 Downing Street

Theresa May has led tributes to David Cameron at his last cabinet meeting before she moves into 10 Downing Street on Wednesday.

Ms May spoke of the “warmth and respect” the prime minister had earned from colleagues for the way he had led the country through such difficult times as the aftermath of the financial crisis and the increasing threat of terrorism.

Mr Cameron will take prime minister's questions at the House of Commons for the last time today, before travelling to Buckingham Palace to present his resignation to Queen Elizabeth. Ms May will go to the palace shortly afterwards and is expected to return to Downing Street as prime minister by early evening.

Ms May has offered no hints about the make-up of her new cabinet, or how she intends to balance the ambitions of pro- and anti-Brexit ministers.

As an EU commissioner urged Ms May to “accelerate” Brexit negotiations by invoking article 50 of the EU Treaty, which starts formal talks, one of her key allies said the process of leaving could take longer than the second World War.

Future treaty

Foreign secretary

Philip Hammond

told MPs that, after the two years of negotiations stipulated by article 50, it could take four more to get any agreement ratified.

“The concern is this. If a future treaty between the UK and the EU 27 is deemed to be a mixed competence, it will have to be ratified by 27 national parliaments. I think I am right in saying the shortest time in which that has been done in any EU treaty is just under four years, and that is after taking into account the time it has taken to negotiate,” he said.

An EU treaty is deemed to be a “mixed competence” if it deals with matters that are the preserve of member states, as well as those for which the EU is collectively responsible, such as trade.

Some MPs have suggested that Britain should move quickly to negotiate new, post-Brexit trade deals with other countries but Mr Hammond warned that such a move could be in breach of its international obligations.

“Until we have served an article 50 notice, we remain a full, participating member of the EU and our ability to negotiate new trade agreements is restricted by the continued application of EU law until we have negotiated our exit from the EU,” he said.

Formal talks

Ms May has said she will not rush into triggering article 50, suggesting she will wait until next year to start the clock on formal exit talks.

But the EC's economic and financial affairs commissioner Pierre Moscovici said yesterday that after her swift elevation to the premiership, she should accelerate the negotiations with EU partners.

“The Conservative Party went fast. David Cameron was supposed to be replaced in September, we are only July, so why lose those two months?” he said.

"It's possible that the process of the discussion with the European Union also accelerates. That's what I think a lot of people expect and hope and call for."