US President Donald Trump’s unprecedented second state visit to the United Kingdom has officially begun, with pomp and ceremony being met with protests.

Mr Trump and his wife Melania were greeted by King Charles III, Queen Camilla, Prince William and Catherine, Princess of Wales, in the Walled Garden of Windsor Castle as he stepped off Marine One helicopter.

Prince and Princess of Wales Donald Trump Melania Trump

The Prince and Princess of Wales were the first to greet Donald Trump and Melania Trump at Windsor Castle on Wednesday. (Reuters: Aaron Chown/Pool)

As the president shook hands with the King, a 41-gun salute was fired simultaneously from six World War One-era guns on the castle’s east lawn, as a similar display occurred at the Tower of London, in the centre of the capital.

Some 120 horses, and 1,300 members of the British military took part in the ceremony, which UK officials say marked the largest military ceremonial welcome for a state visit to Britain in living memory.

Ceremonial welcome Donald Trump UK visit

The sprawling and historic grounds of Winsdor Castle were the stage for day one of Donald Trump’s state visit to Britain.

  (Reuters: Chris Jackson/Pool)

The Trumps and the royals then embarked on a carriage procession through the Windsor estate towards the nearly 1,000-year-old castle.

The pair chatted in the short journey to the castle’s quadrangle, where they inspected a guard of honour.

Horse-drawn carriage procession Donald Trump

The horse-drawn procession journeyed through the sprawling Windsor Estate.
  (Reuters: Henry Nicholls/Pool)

Britain is going the extra mile to dazzle and flatter the unpredictable US president with an extraordinary show of pomp and pageantry as it tries to keep him onside during a host of international crises.

The UK will try and charm Trump this week with ‘all his favourite things’

The US president has been given something no other world leader has ever received: a second state visit invitation from Buckingham Palace. But assessing the trip’s success means looking beneath the pomp and pageantry.

The military welcome was even bigger than when Queen Elizabeth II hosted Mr Trump on his previous state visit in 2019.

He will also get the first joint flypast by US and UK fighter jets at an event of its kind, featuring a US and British F-35 military jets and the Royal Air Force’s Red Arrows display team.

While the US president visited Windsor, protesters hit the streets of London and outside the estate angry about his visit.

Some 1,600 officers were deployed to deal with a demonstration by the “Stop the Trump Coalition” in London alone.

Anti-Donald Trump protests UK

Demonstrators rallied outside Windsor Castle as Donald Trump was treated to a warm welcome inside. (Reuters: Hannah McKay)

State visit designed to flatter Trump

The Trumps will lay a wreath on the tomb of Queen Elizabeth II, who died in 2022, and the president and King Charles will wrap up Wednesday with a white-tie state banquet, where they are due to make speeches.

It’s all designed to appeal to a US leader who this year crowed “LONG LIVE THE KING!” about himself on social media before the White House posted a fake magazine cover of him wearing a crown.

British Prime Minister Keir Starmer will be hoping Mr Trump leaves on Thursday feeling the warm glow of royal soft power — but there are no guarantees.

Four people stand in formal attire standing side by side

Donald Trump salutes as he stands beside King Charles III and Queen Camilla with first lady Melania Trump, far left, during the US national anthem. (Reuters: Kirsty Wigglesworth/Pool)

Mr Trump appeared to be feeling the love as he arrived by helicopter at the US ambassador’s official residence in London on Tuesday with First Lady Melania Trump.

“A lot of things here warm my heart,” said the president, whose mother hailed from Scotland and who owns two golf resorts in the country.

He described the King, 76, who is undergoing treatment for cancer, as “my friend”.

King Charles Donald Trump royal carriage Windsor

King Charles and Donald Trump chatted during their carriage journey. (Reuters: Toby Melville/Pool)

The Republican may also relish a chance to escape a turbulent period at home in the United States, where the killing of right-wing activist Charlie Kirk has caused deep turmoil.

But the spectre loomed of late sex offender Jeffrey Epstein, who is providing domestic headaches for both Mr Trump and Sir Keir Starmer and who has caused the royal family considerable embarrassment.

UK protesters arrested after beaming Epstein video ahead of Trump visit

The shots included Donald Trump’s mugshot, portraits of Epstein, newspaper headlines, and footage of the two men dancing together.

Police arrested four people after they projected images of Mr Trump and Epstein onto Windsor Castle late Tuesday.

Mr Starmer will host Mr Trump on the second day of the visit on Thursday at his country residence, Chequers.

The pair will be buoyed by British pharmaceutical group GSK’s announcement that it will invest $30 billion in the United States over the next five years but talks could turn awkward on several fronts.

The UK prime minister in particular faces political troubles at home, after sacking his UK ambassador to Washington, Peter Mandelson, over a furore involving the diplomat’s connection to the late Epstein.

ABC/wires