Donald Trump launched a trademark Twitter broadside at London Mayor Sadiq Khan as he touched down in the UK for a state visit that will see him meeting the Queen and other senior royals, as well as Theresa May in her final days as Prime Minister.

The US President and the First Lady were greeted by Foreign Secretary Jeremy Hunt and US ambassador to the UK Woody Johnson at Stansted Airport on Monday morning as they began their three-day trip.

Mr Trump arrived in Britain having already created a considerable degree of political turbulence with comments on the Tory leadership race, Brexit and the Duchess of Sussex.

Speaking to reporters just before he left the US, he praised Boris Johnson and Nigel Farage, talked up the prospect of a Brexit trade deal, and rebuked Mr Khan, who on Sunday described the president as “just one of the most egregious examples of a growing global threat” and compared the language he has used to that of the “fascists of the 20th century”.

And as he landed he mis-spelled the London Mayor’s name, writing: “@SadiqKhan, who by all accounts has done a terrible job as Mayor of London, has been foolishly “nasty” to the visiting President of the United States, by far the most important ally of the United Kingdom. He is a stone cold loser who should focus on crime in London, not me……

“…Kahn reminds me very much of our very dumb and incompetent Mayor of NYC, de Blasio, who has also done a terrible job – only half his height. In any event, I look forward to being a great friend to the United Kingdom, and am looking very much forward to my visit. Landing now.”

President Trump state visit to UK – Day One
US President Donald Trump and his wife Melania arrive at Stansted Airport in Essex.

Asked before he left if he planned to meet Boris Johnson during the trip, he said: “Well, I think I may meet with him. He’s been a friend of mine. He’s been very nice. I have a very good relationship with him.”

He went on: “I have a very good relationship with Nigel Farage, with many people over there (in the UK) and we’ll see what happens. I may meet with him. They want to meet. We’ll see what happens.”

Ahead of the visit, he called on Britain to leave the European Union without a deal if Brussels refuses to meet its demands and urged the Government to send Mr Farage into the negotiations.

The controversy was further exacerbated on Sunday when the US ambassador to the UK, Woody Johnson, suggested the NHS would be on the table in post-Brexit trade talks.

Addressing the prospect of a transatlantic trade deal, Mr Trump said: “(We’re) going to the UK. I think it’ll be very important. It certainly will be very interesting. There’s a lot going on in the UK. And I’m sure it’s going to work out very well for them.

“As you know, they want to do trade with the United States, and I think there’s an opportunity for a very big trade deal at some point in the near future. And we’ll see how that works out.”

The Trumps will head to Buckingham Palace for a reception with the Queen, the Prince of Wales and the Duchess of Cornwall.

The Duke of Sussex will also attend a private lunch at the palace – although his wife, who is on maternity leave, will be at home with their four-week-old son, Archie.

In a potentially awkward start to the trip, Mr Trump has already had to deny making “bad” comments about Meghan.

He tweeted to say that he did not brand the American former actress “nasty” when he was recently confronted with comments she made before the 2016 US elections saying she would leave the country if he won.

He blamed the “Fake News Media” for the reports and, asked at the White House on Sunday evening if he was willing to apologise to the royal family, or to clarify the comments made to the Sun’s political editor, Mr Trump replied: “No, I made no bad comment. Thank you.”

A string of events have been prepared to honour the couple, including a ceremonial welcome in the Buckingham Palace garden before Mr Trump has the opportunity to inspect the Guard of Honour.

Elsewhere, royal gun salutes will fire in Green Park and at the Tower of London to mark the Trumps’ arrival.

They will then visit Westminster Abbey where the president is due to lay a wreath at the Grave of the Unknown Warrior.

Donald Trump visit to UK
Donald Trump will meet the Queen and other members of the royal family (Chris Jackson/PA)

Mr Trump and wife Melania are also due to have tea with Charles and Camilla at Clarence House.

The day is due to conclude with a state banquet at Buckingham Palace at which both the Queen and Mr Trump will give speeches.

Mr Trump’s arrival in the capital is due to be followed by a protest through central London against the visit on Tuesday, with the Trump Baby blimp made for his visit last year due to put in an appearance.