U.S. President Donald Trump has kicked off a three-day State Visit to the U.K. It’s been a day of pageantry as the Queen hosted Trump at Buckingham Palace. But even before arriving, Trump broke with diplomatic traditions, as CGTN’s Richard Bestic reports.

Touching down in the back garden of Buckingham Palace, President Trump begins a State Visit three years on from the invitation first being made.

Meeting Britain’s Queen Elizabeth the Monarch wreathed in smiles.

Three days of Pomp and Ceremony ahead, President Trump reportedly a big fan of such pageantry.

In a London park nearby, the sound of canons fired in salute to the American Commander-in-Chief.

Despite all that, President Trump not happy.

Even before he’d landed the President had launched an angry Twitter tirade against the Mayor of London, Sadiq Khan, who he called a ‘stone cold loser.’

Furious Khan was publicly disapproving, saying: “My point is this, that some of the things that Donald Trump has done over the last two or three years, Londoners find abhorrent and offensive. There are so many things about President Donald Trump’s policies that are the antitheses of our values in London and also our values as a country.’

There are a raft of potential flashpoints on this Royal visit, not least over the treatment of the Chinese communications giant Huawei, President Trump threatening to pull shared intelligence if Britain gives Huawei a role in its plans for 5G. And, of course, differences over climate change, the Iran nuclear deal, and Brexit.

President Trump is only the third U.S. president to be given a full state visit in Queen Elizabeth’s 66-year reign. Originally intended to boost trade relations in a post-Brexit world.

That didn’t happen and, with U.K. Prime Minister Theresa May leaving office, the U.S. President arrived amid a full-blown leadership election.

Upending diplomatic convention by endorsing former Foreign Secretary Boris Johnson as the best person to take over.

Ahead of his visit, he also told the UK to get tough with the European Union over Brexit – a bitter issue that’s caused unrivaled strains on the British political system.

As the Trump tour is only just underway, UK government Ministers are reported to be nervously on the edge of their seats.