LONDON — Queen Elizabeth II greeted President Trump with a warm smile and a booming double gun salute at Buckingham Palace on Monday, as he began his first state visit to the U.K.

They set aside the controversy of his arrival tweets — criticizing the mayor of London — to focus on the ceremony, pomp, and pageantry of the formal occasion.

Trump and the first lady arrived aboard Marine One to be met first by Prince Charles and his wife Camilla, before being welcomed by the queen, 93, who looked vibrant in mint green.

A handful of Trump supporters waiting outside Buckingham Palace erupted in a spontaneous chorus of “For He’s a Jolly Good Fellow,” in a small reminder that for all the expected protests Trump is more popular here than in many other European countries. They ended with a "hip hip hooray."

Caden McClure, 18 from Tulsa, was among the crowds of tourists thronging the Mall for a glimpse of the president. He dismissed the opposition to the visit and said Britain was just as divided as the U.S.

“It’s an indication of the UK’s opinion of him but it’s not the only opinion,” he said. "It's the same at home."

In the minutes after his arrival, soldiers from the King’s Troop Royal Horse Artillery fired 82 blank rounds at 10-second intervals, 41 each for Trump and the queen, sending booms around central London. A head of state gets a 21-gun salute with an extra 20 rounds fired when they are fired from a national park.

Trump then reappeared with the first lady before inspecting the guard of honor with Prince Charles in the garden of Buckingham Palace.

The queen was due to host a private lunch at the palace for the president and the first lady followed by a chance to view some special items from the royal collection.

Officials said the queen was planning to show artifacts that were of particular relevance to the U.S. and the “special relationship.”

It is the 113th time the queen has welcomed a world leader for a state visit. She will not have met many quite like Trump before.

Not only is he an unpredictable guest — wading into the Conservative leadership battle at the weekend and tweeting his contempt for the mayor of London before Air Force One even landed — he arrives at an awkward moment for both countries.

[Also read: Trump denounces 'stone cold loser' London mayor as he arrives in Britain for state visit]

He faces a clamor for impeachment at home while the host government is about to lose its prime minister after months of political turmoil over Brexit.

And there are real sources of tension between the U.S. and U.K, whether on handling Iran or buying hardware from Huawei.

As a result officials on both sides have emphasized the ceremonial nature of a state visit. Trump will enjoy an audience with the queen and take part in D-Day commemoration events in London and Normandy.

“There is no better time to have a state visit to the United Kingdom than the 75th anniversary of D-Day,” said a senior administration official.

Protesters plan to make their feelings clear. They are planning to assemble outside Buckingham Palace as guests begin arriving for the state banquet.

But the main event comes on Tuesday when organizers hope some 250,000 people converge on Trafalgar Square.

Mohammed Ateek, of The Stop Trump Coalition said, “The UK should be turning its back on Trump’s harmful and divisive politics and not honouring his agenda with a state visit. We will be standing up to normalizing a racist, misogynist, Islamophobic leader who is a climate crisis denier.”