President Donald Trump and First Lady Melania Trump have arrived in the United Kingdom for their first state visit.

Donald Trump began the visit on a high note, calling London Mayor Sadiq Khan a “stone cold loser” on Twitter before Air Force One had even landed.

“….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!”

He and first lady Melania Trump then took Marine One, the presidential helicopter, to Buckingham Palace, where they were greeted by Prince Charles and his wife Camilla.

Mr Trump inspected an honour guard with Britain’s Prince Charles. The pair have divergent views on climate change. (AP: Victoria Jones)

They walked a short distance to a covered entrance, where the queen, dressed in a chartreuse dress and matching hat, shook their hands and smiled before ushering the couple inside. The five-person group reappeared a few minutes later for a welcoming ceremony conducted by the Guard of Honour, which performed American classics including the national anthem, “The United States Air Force,” “The United States Army Goes Rolling Along,” and “The Marines’ Hymn.”

Last summer, London braced itself for 100,000 protestors when Trump paid a working visit to the country, and this year, the city is bracing itself for another big demonstration of Trump opponents.

The British population overwhelmingly opposes Trump and his ideas, but the ruling class recognizes the need of bolstering the relationship with the US while it negotiates Britain’s withdrawal from the European Union.

The Queen showed Mr Trump golfing and US memorabilia from the Royal Collection. (AP: Tolga Akmen)

Mr Trump said the gatherings were “tremendous crowds of well-wishers.”

“Haven’t seen any protests yet, but I’m sure the Fake News will be working hard to find them,” he tweeted.

Trump’s daughter, Ivanka Trump, and her husband, Jared Kushner, accompanied him on the trip.

Ivanka Trump and Jared Kushner accompanied Mr Trump on his state visit. (AP: Frank Augstein)

The Trumps were asked to remain for lunch and a presentation of royal presents.

After lunch, the Trumps will visit a special exhibition in the Picture Gallery including artifacts from the Royal Collection of historical relevance to the United States. Prince Harry will attend the viewing without his wife, Meghan Markle, who is presently on maternity leave following the birth of their baby Archie on May 6.

They then went to Westminster Abbey, the site of coronations and royal marriages, as well as the last resting place of 17 monarchs, plus Isaac Newton, Stephen Hawking, and Charles Darwin. T hey returned to Buckingham Palace for an evening state banquet, where Trump and the queen toasted their nations’ historic connections in battle and peace.

The Trumps place a wreath at the grave of the Unknown Warrior at Westminster Abbey. (AP: Alex Brandon)

“On behalf of all Americans, I offer a toast to the eternal friendship of our people, the vitality of our nations, and to the long, cherished, and truly remarkable reign of her majesty the queen,” Trump said.

The Trumps will also pay a visit to Westminster Abbey on Monday, when Prince Andrew will give them a tour and lay a wreath at the Grave of the Unknown Warrior.

The Queen displayed golfing memorabilia from her family, a photograph of George Washington, and a draft copy of a telegram from George VI to US General Dwight Eisenhower during the D-Day invasion of France.

The major events are meant to highlight the closeness of the two countries’ “special relationship.”

Trump’s weeklong trip will be mainly ceremonial, with a state visit and audience with the queen, D-Day memorial events on both sides of the English Channel, and his first presidential visit to Ireland, which will include a stay at his coastal golf club.