The Prince and Princess of Wales receive US President Donald Trump and First Lady Melania Trump at Windsor Castle in Windsor, Berkshire, on day one of their second state visit to the UK. Picture date: Wednesday September 17, 2025. / Aaron Chown/Pool via REUTERS

King Charles and other British royals greeted Donald Trump on Sept. 17 as the U.S. president's historic second state visit to Britain began with unprecedented pomp, intense security, technology investments and protests.

Trump and his wife Melania arrived at Windsor Castle, the oldest and largest inhabited castle in the world and family home to British monarchs for almost 1,000 years. He was met by the monarch, his wife Queen Camilla, heir Prince William and his wife Kate before a carriage procession through the grounds.

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Ahead of a lavish banquet there will be a military flypast, part of what Britain has said would be the largest military ceremonial welcome for a state visit in living memory.

Trump, an overt royal fan, has made little secret of his delight at being not just the first U.S. leader, but the first elected politician to be invited by a British monarch for two state visits.

On his arrival, he told reporters he loved Britain. "It's a very special place," he said.

UK HOPES VISIT WILL CEMENT 'SPECIAL RELATIONSHIP'

Prime Minister Keir Starmer is hoping to use that sentiment to Britain's advantage as his government seeks to cement the two nations' "special relationship", deepen economic ties, secure billions of dollars of investment, discuss tariffs and press the U.S. president on Ukraine and Israel.

Companies including Microsoft, Nvidia, Google and OpenAI have already pledged 31 billion pounds ($42 billion) in British investments over the next few years, in AI, quantum computing and civil nuclear energy.

Starmer also wants further progress on trade, after Britain secured the first deal with Trump to lower some tariffs. Talks may touch on remaining levies on steel, whisky and salmon.

"They want to see if they can refine the trade deal a little bit," Trump said when he left the White House for Britain on Sept. 16.

But while Starmer is banking on the unrivalled royal allure helping cajole the anglophile president, whose mother came from Scotland, many pitfalls for Britain's prime minister remain.

Polls show Trump is widely unpopular in Britain and Starmer, faced with plummeting poll ratings of his own and economic woes, will need to show that his royal trump card can reap benefits.

PROTESTERS PULL OFF EPSTEIN STUNT DESPITE HIGH SECURITY

Awkward questions about late sex offender Jeffrey Epstein could also come to the fore.

Starmer, last week, sacked Peter Mandelson as Britain's ambassador in Washington over his ties to Epstein, which could lead to questions for both Starmer and Trump, whose own relationship with the financier has also come under scrutiny.

While there was a massive police operation in place in Windsor, police said four people had been arrested on Sept. 16 after images of Trump alongside Epstein were projected onto one of the castle's towers. Trump was not there at the time.

Large protests are also expected in London on Sept. 17 with 1,600 officers deployed to deal with a demonstration by the "Stop the Trump Coalition".

Commuters in the capital had mixed views about the visit, with some angry about the invitation and others saying it was smart politics and a good use of Britain's soft power.

"We're looking to sort of make the best of a bad situation," said lawyer Kirstie Robertshaw, 54.

TRUMP TO BE DAZZLED BY PAGEANTRY

Sept. 17 will be dominated by ceremony. Trump and his wife Melania were first greeted by the king's "very handsome" elder son Prince William - as the president has called him - and Kate.

Charles and his wife Queen Camilla then joined the Trumps on the carriage procession, with the route lined by 1,300 British service personnel.

The president, occasionally chatting and smiling with the king, then inspected a guard of soldiers wearing scarlet uniforms and bearskin hats.

Later, the royals will show the president and first lady historical items from the Royal Collection relating to the U.S., before the Trumps visit St George's Chapel, the final resting place of Queen Elizabeth, who hosted Trump for his first state visit in 2019, where he will lay a wreath on her tomb.

There will be a flypast including UK and U.S. F-35 military jets, a symbol of U.S.-British defence collaboration, before an opulent state banquet where the king and president will make speeches.

For Charles himself, the visit might provoke mixed emotions. He has little obviously in common with Trump, from his 50 years championing environmental causes to his efforts to bring harmony between religions and his recent steadfast support for Canada, where he is head of state.

But the occasion will also afford him the greatest global attention since his coronation.

"If it goes well ... I think this will go down as the most consequential event in his reign," said historian Anthony Seldon.