Trump wants a US-UK trade deal ‘within the next year’, Johnson claims

But Johnson has played down the prospects of a transatlantic deal within that timeframe and warned that a deal with the “protectionist” US would not be “plain sailing”.

The president said: “We’re going to do a very big trade deal, bigger than we’ve ever had with the UK and now at some point they won’t have the obstacle, they won’t have the anchor around their ankle, because that’s what they have.”

He said he wanted a deal done “quickly” because in the past he had been “stymied” under Theresa May.

He added: “This is a different person and this is a person that’s going to be a great prime minister, in my opinion.”

But the prime minister told the president there would be “tough talks” ahead and played down the prospect of a rapid deal.

Johnson told ITV: “There’s an opportunity to do a great free trade deal with the United States.

“The president is very gung-ho about that and so am I.”

But he continued: “I don’t think people realise quite how protectionist” the US market can be.

“They want to do it within a year, I’d love to do it within a year, but that’s a very fast timetable,” he said.

Johnson also had talks on Brexit at the G7 with European Council president Donald Tusk.

A senior UK official said the pair would meet again in September at the United Nations General Assembly.

The official said: “The prime minister repeated that the UK will be leaving the EU on October 31, whatever the circumstances. We must respect the referendum result.”

Johnson said the UK would work in an “energetic and determined way to get a better deal and we are very willing to sit down to talk with the EU and member states about what needs to be done to achieve that”.