MercoPress. South Atlantic News Agency

UK and EU will remain the “best of friends”, but it is impossible to reach a trade deal by the end of 2020, EC president

Mrs. von der Leyen said if the deadline was not extended it was not a case of “all or nothing”, but of priorities. Boris Johnson has insisted in December 2020.

UK and the EU will remain the “best of friends” but they will “not be as close as before” after Brexit, the new European Commission president has said. Speaking ahead of talks with the PM, Ursula von der Leyen warned it would be “impossible” to reach a comprehensive trade deal by the end of 2020.

She said if the deadline was not extended it was not a case of “all or nothing”, but of priorities. Boris Johnson has insisted a deal is possible by December 2020.

After their meeting in No 10, a Downing Street spokesman said talks had been “positive”, but the PM had been “clear” the process of negotiation would not be extended.

After its 31 January exit, the UK will enter into an 11-month transition period in which it will largely follow EU rules but will not have any representation in the bloc's institutions. This period will come to an end on 31 December.

Only when the UK leaves the EU can the two sides begin talks on their future economic relationship.

Mr Johnson told Mrs von der Leyen he “wanted a positive new UK and EU partnership, based on friendly co-operation, our shared history, interests and values”, as well as a “broad free trade agreement covering goods and services, and cooperation in other areas”.

He also said the UK was ready to start negotiations “as soon as possible” after 31 January.

Speaking at the London School of Economics earlier in the day, Mrs. von der Leyen said the EU was “ready to negotiate a truly ambitions partnership with UK” but she warned of “tough” talks ahead.

“We will go as far as we can, but the truth is that our partnership cannot and will not be the same as before and it cannot and will not be as close as before because with every choice comes a consequences with every decision comes a trade off.”

Mrs von der Leyen, a former German defense minister, took over from Jean-Claude Juncker at the start of December. She was a student at the LSE in the 1970s. She also attended the same school as Mr. Johnson in Belgium - something the prime minister highlighted as they posed for photos in Number 10.

Mrs von der Leyen said she hoped the new trading relationship would be based on “zero tariffs, zero quotas, zero dumping”. But she said: “Without the free movement of people you cannot have the free movement of capital and services.

”The more divergence there is the more distant the partnership will be.“

Mrs von der Leyen also warned that without an extension of the transition period beyond 2020 ”you cannot expect to agree every single aspect of our new partnership”.