Dr Greg Atury is a trade expert and has written a book with Peter Navarro, President Trump's trade adviser.

Speaking to BBC Radio 4's Today Programme, he describes Donald Trump as “a great negotiator”.

He says there was a "great deal of appetite" in the US for a trade deal with the UK.

"No one wants to see the relationship go badly," he adds.

Concerning the protests, Dr Atury says the president was used to criticism.

Image source, PA

A number of demonstrations - both pro- and anti-Trump - are expected to take place today:

• The #BringTheNoise Women's March will start at 11:00 BST in central London and finish outside the Houses of Parliament
• The "Together against Trump" will take place in the afternoon, also in central London
• Up to 3,000 are expected to gather in Glasgow's George Square to protest against the president's visit
• Republicans Overseas UK is hosting a rally at a venue on Pall Mall, London
• A pro-Trump reception will be held in Hammersmith, London by the Bow Group, a think tank

Shadow foreign secretary Emily Thornberry said it was "extraordinarily rude of Donald Trump to behave like this".

Speaking to ITV's Good Morning Britain, the Labour MP said: "She is his host. What did his mother teach him? This is not the way you behave,"

"You need to stand up to him. She [Theresa May] is letting down our country by not standing up to him," she added.

Laura Kuenssberg
BBC political editor

President Trump drives a bulldozer through the government's central claims about their compromise - that the UK would be able to get decent trade deals with the wider world, while sticking to the EU rules.

A lot of this visit has been carefully choreographed, as the prime minister and the president dance around each other.

But if the president really wanted to help her build support for her controversial compromise, this isn't the way to do it.

Read more from Laura

The Sun’s political editor, Tom Newton-Dunn, who carried out the explosive interview with Mr Trump, said the US president is “sensitive” and knows about the baby blimp.

“His mood was nervous, I think, his arms were crossed a lot,” Mr Newton-Dunn told BBC Radio 4’s Today programme.

“He knows an awful lot about Britain. But he’s really quite stung by the criticism he’s been getting, the treatment he was going to get when he arrived. “He knew all about the baby blimp. I think it hurt him.”

He added that Mr Trump “understands Brexit philosophically and ideologically” and has been a Brexiteer since the 1980s.

Image source, European Photopress Agency

BBC correspondent Gary O'Donoghue said Mr Trump had really hit Theresa May where it hurts.

He described a trade deal with the US as "the pot of gold at the end of the rainbow".

By casting doubt on the feasibility of such a deal, he said the US president had "not just thrown a spanner in the works but brought the whole engine to a grinding to a halt."

"Goodness knows what the chemistry is going to be like when they have to stand next to each other," he said.

Donald Trump's comments in the Sun, external about Theresa May's Brexit plans have made the headlines, but what else did he say?

• Ex-Foreign Secretary Boris Johnson would make a "great" future prime minister
• London Mayor Sadiq Khan had done "a bad job" on terrorism and crime
• "I used to love London as a city. I haven’t been there in a long time. But when they make you feel unwelcome, why would I stay there?"
• The Queen is "a tremendous woman" who "has really never made a mistake"
• Theresa May is "a very good woman" and he denied calling her "a bossy schoolteacher"

• Theresa May and Donald Trump will visit a defence site this morning
• They will then travel to the prime minister's country residence for bilateral talks
• Next, the president, with his wife Melania, head to Windsor Castle for tea with the Queen
• Finally, the couple will head to Scotland to spend the weekend at Mr Trump's golf resort

The president's interview to the Sun provoked strong reaction.

Conservative MP Sarah Wollaston described his comments "divisive, dog-whistle rhetoric", and added: "If signing up to the Trump world view is the price of a deal, it's not worth paying."

Labour MP Phil Wilson said: "She [the prime minister] has pinned all her hopes on getting a trade deal with Donald Trump but instead the US president has explicitly backed and strengthened those who advocate a disastrous no-deal Brexit."

However No 10 Downing Street have yet to comment.

White House spokeswoman Sarah Sanders said the president "likes and respects Prime Minister May very much", adding that he had "never said anything bad about her".

Image source, AFP/ Getty Images

The president has been making diplomatic waves overnight.

In an interview with the Sun newspaper,, external he said the UK will "probably not" get a trade deal with the US, if the prime minister's Brexit plan goes ahead.

He also former Foreign Secretary Boris Johnson - who resigned in protest at the Brexit plan - would make a "great prime minister", adding "I think he's got what it takes".

And that's where our coverage ends.

We'll leave the Mays, the Trumps, the cabinet ministers and business leaders to lick the last of the clotted cream off their silver spoons.

But we'll be back with more for you tomorrow - Friday - when Mrs May will hold talks with the president at Chequers, her country residence, and the Trumps can look forward to tea with the Queen.

Marches and protests are also planned in London, Glasgow and other UK cities.

Image source, Getty Images

The evening's venue, Blenheim Palace, near Oxford, is the ancestral home of the Spencer-Churchill family, and the birthplace of Winston Churchill.

“We know he’s a fan of Winston Churchill,” US ambassador Woody Johnson told me and others before the president's trip.

“We thought it would be nice to do a dinner there. Outside London.”

Some critics of the US administration say that's partly why the site was chosen - it's the birthplace of Churchill and, equally importantly, it's located outside the capital, where demonstrators are supposed to gather.

However, hundreds of protesters are currently lining the streets outside the estate's gates.

Image source, Reuters

Feeling hungry?

Mr and Mrs Trump will be treated to Scottish salmon, English Hereford beef fillet and strawberries with clotted cream ice-cream at the lavish dinner.

Theresa and Philip May stand alongside Donald and Melania Trump on the steps of the palace to listen to Liberty Fanfare, the National Emblem, and a special arrangement of Dear Lord and Father of Mankind with Amazing Grace, played by the guards.

There are bagpipes mixed in to the arrangement, in a nod to Mr Trump's Scottish connections.

Image source, Getty Images

Mrs May, in high heels, walks alongside Mr Trump the short distance to the palace steps, but appears to struggle slightly with the cobbled ground.

At the steps, the two hold hands, in an echo of the hand-holding at the White House last year.