Donald Trump has arrived for talks with Theresa May just hours after lobbing a political grenade that has left the Prime Minister badly wounded.

The US president humiliated Mrs May by criticising her approach to negotiations, lavishing praise on Boris Johnson days after he walked out of her Cabinet and warning her Brexit plan could “kill” any UK-US trade deal.

Mr Trump’s comments emerged as Mrs May pulled out all the stops to entertain the president and wife Melania with an evening of pomp and ceremony at Blenheim Palace.

The PM and the president will now be locked in hours of talks at Chequers that will culminate in what promises to be an awkward press conference at her country residence.

Two ministers broke cover to make their displeasure at Mr Trump’s comments known.

Education minister Sam Gyimah said: “Where are your manners, Mr President?”

Culture minister Margot James tweeted: “No Mr President @POTUS Boris Johnson would make a terrible PM.”

Donald Trump visit to UKUS President Donald Trump takes the hand of Prime Minister Theresa May (Will Oliver/PA)

Protesters took the streets in London to demonstrate against the president’s visit – and in Parliament Square, a Trump baby blimp was raised up in the air.

Mr Trump sent shockwaves through Westminster when he gave an explosive interview to The Sun where he said he would have carried out Brexit negotiations “much differently” and claimed the Prime Minister did not listen to his advice.

He said: “If they do a deal like that, we would be dealing with the European Union instead of dealing with the UK, so it will probably kill the deal.

“If they do that, then their trade deal with the US will probably not be made.”

Donald Trump visit to UKThe US presidential cars arrive at Blenheim Palace in Oxfordshire (Will Oliver/PA)

Addressing the 100-strong dinner at Blenheim Palace, the Prime Minister said there was an “unprecedented” opportunity to do a deal that boosted jobs and growth in both countries.

But Mr Trump appeared to link Brexit to the current trade dispute between the US and EU over steel and aluminium.

He told The Sun Mrs May’s plan would affect trade “unfortunately in a negative way”. He added: “We have enough difficulty with the European Union.

“We are cracking down right now on the European Union because they have not treated the United States fairly on trading.

“No, if they do that I would say that that would probably end a major trade relationship with the United States.”

Donald Trump visit to UKAir Force One touches down at Stansted Airport (Joe Giddens/PA)

Mr Trump went on to say Mr Johnson, who quit as foreign secretary over the Chequers plan, was “a great representative for your country”.

Asked if he could become prime minister, he added: “Well I am not pitting one against the other. I am just saying I think he would be a great prime minister. I think he’s got what it takes.”

In a statement following the publication of the Sun interview, the White House press secretary said Mr Trump “likes and respects Prime Minister May very much” and he “never said anything bad about her”.