LONDON   -   Donald Trump breezed into Buckingham Palace onboard Marine One on Monday morning, as Tory leadership contenders braced themselves for presidential interventions in the race.

The US president and the first lady, Melania Trump, landed on the Queen’s lawn in their helicopter for the full British bells and whistles state visit, including two 41-gun salutes, a guard of honour and a banquet.

There was even a wall – the high one which encloses Buckingham Palace gardens – which served to keep Trump well away from the public at the start of his three-day visit, most of which will be conducted behind closed doors and well away from the planned protests.

Security concerns meant the ceremonial welcome was held on the palace lawn instead of nearby Horse Guards Parade. So there was no carriage ride, thus no risk of a repeat of the welcome afforded China’s president, Xi Jinping, who ran the gauntlet of mass protests along the Mall.

The Prince of Wales and Duchess of Cornwall greeted the presidential couple. The Trumps then walked together to meet the Queen, who was waiting on the palace steps, and the first lady did an excellent job of aerating the lawn with her spiked high heels.

Accompanied by Prince Charles, and to a medley of American service tunes played by the band of the Grenadier Guards, the president then inspected the guard of honour by the Nijmegen Company Grenadier Guards. His daughter Ivanka and her husband, Jared Kushner, watched the ceremony from a palace balcony.

Earlier, Air Force One had touched down at Stansted airport where the president was met by the foreign secretary, Jeremy Hunt. Immediately on landing Trump launched into a Twitter attack on the mayor of London, Sadiq Khan. He tweeted that Khan was a “stone cold loser” in response to Khan’s critical article in Sunday’s Observer. The mayor’s office called Trump’s comments “childish insults” beneath the office of president.

The long-delayed state visit is the 113th hosted by the Queen, and is a meeting between two dynasties, one ancient, one fledgling. In a departure from protocol, Trump is combining the official visit with a family jaunt, reportedly bringing four of his five children: Ivanka, Donald Jr, Eric and Tiffany.

An upgrade on his previous “working visit”, where he had tea with the Queen, he now gets his long-desired white tie and tiara banquet. Around 170 guests who have cultural, diplomatic and economic links with the US will join the Trumps and royals in the grand ballroom at Buckingham Palace, to dine off the silver gilt of the Grand Service made for George IV. The Labour leader, Jeremy Corbyn, and the Liberal Democrat leader, Sir Vince Cable, both declined to attend. Donald Trump inspects an honour guard at Buckingham Palace. The controversial visit, hastily offered by Theresa May after Trump’s inauguration, brings down the curtain on her troubled premiership.

Both the Tory leadership contender Boris Johnson and the Brexit party leader, Nigel Farage, are expected to attend Trump’s return banquet on Tuesday, at the US ambassador’s London residence. In pre-visit interviews Trump made no attempt to hide his admiration for both men. In a further diplomatic gaffe, he also claimed other leadership candidates had sought out his endorsement.

Amid a huge security operation, there is little opportunity for the public to see the president as he is travelling by helicopter to most venues for engagements held behind closed doors.

Before his visit he publicly criticised May’s handling of Brexit and he is likely to be vocal on the subject of Huawei. The royals will undoubtedly have to strain every diplomatic sinew.