U.S. President Donald Trump and first lady Melania Trump disembark Air Force One as they arrive for a state visit to Britain, at London Stansted Airport near London, Britain, September 16, 2025. REUTERS/Kevin Lamarque

By Phil Noble

WINDSOR, England (Reuters) - U.S. President Donald Trump formally begins his unprecedented second state visit to Britain on Wednesday with the royal pomp a grand veneer to key diplomatic talks, and as difficult questions about Jeffrey Epstein linger.

King Charles and the royal family will roll out the red carpet for the president when he arrives at Windsor Castle, the oldest and largest inhabited castle in the world and family home to British monarchs for almost 1,000 years, with a carriage procession, gun salutes, a military flypast and lavish banquet.

Britain says it will 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 visits.

"I Love King Charles," he posed on his Truth Social account in February. He added on arrival: "I have a lot of things here that ... they warm my heart. It's a very special place."

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 use the trip 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.

While security for the visit will be tight, with a massive police operation in place in Windsor and 1,600 officers deployed in London to deal with a protest by the "Stop the Trump Coalition", Trump's arrival prompted a protest in Windsor.

Police said four people were arrested on Tuesday following a projection of images of Trump alongside late sex offender Epstein onto one of Windsor Castle's towers. Trump was not in Windsor at the time.

The arrests were for malicious communications following an "unauthorised projection", which police described as a stunt.

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

TECH PACT TO BOOST AI, QUANTUM COMPUTING

The visit has already delivered a new technology pact between the two countries which will boost ties in AI, quantum computing and civil nuclear energy. Microsoft has pledged 31 billion pounds ($42 billion) in UK investments.

Starmer will also be looking for further progress on tariffs.

"Basically, I'm there also on trade. They want to see if they can refine the trade deal a little bit. We made a deal, and it's a great deal. And I'm into helping them," Trump said when he left the White House for Britain on Tuesday.

"They'd like to see if they could get a little bit better deal, so we'll talk to them."

TRUMP TO BE DAZZLED BY PAGEANTRY

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

Charles and his wife Queen Camilla will then join the Trumps on a carriage procession through the grounds of the castle, with the route lined by 1,300 British service personnel.

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.

Later there will be a flypast by military aircraft before the state banquet where the king and president will deliver 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.

"I don't think anyone could seriously make a case that President Trump and King Charles III are naturally aligned in their views on really anything at all. And yet expect the king to play a consummately professional role," said historian Anthony Seldon.

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

On Thursday, the action will move to Starmer's Chequers country residence where the focus will be on geopolitics.

($1 = 0.7333 pounds)

(Additional reporting by Elizabeth Piper, Paul Sandle and Alistair Smout; writing by Michael Holden; editing by Alexandra Hudson and Ros Russell)