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US President Donald Trump has arrived at Windsor Castle to meet senior members of the Royal Family on the first full day of his state visit.

He was greeted alongside the first lady by the Prince and Princess of Wales before being formally welcomed by King Charles and Queen Camilla.

The King and Queen then joined them for a carriage procession through the Windsor estate, which will be followed by a flypast and a state banquet later in the day.

Trump touched down in London late on Tuesday for the historic second visit, which will involve a crowded mix of royal pageantry, trade talks and international politics.

The King and President Trump were deep in conversation as they met outside Windsor Castle, which continued as they stepped into a royal carriage for the procession towards the castle.

Queen Camilla and Melania Trump travelled together in a separate coach, followed by Prince William and Princess Catherine.

Some of the most senior figures in Trump's administration - including his Secretary of State Marco Rubio and overseas envoy Steve Witkoff - followed behind in a fourth coach.

The Trumps and the King and Queen were then met by a guard of honour as they stood on a red-carpeted raised platform, before the two men carried out a military inspection.

With 1,300 service men and women from the Army, Royal Navy and RAF set to take part, this was the largest ever guard of honour planned for a state visit to the UK.

The much bigger than usual military line-up for the state visit comes as the UK government will seek to encourage the US to maintain its commitment to Nato and support Ukraine.

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Prime Minister Sir Keir Starmer will later join Trump to watch a US and UK flypast by F-35 jets and the Red Arrows over Windsor, in a display showing the closeness of the military relationship.

The visit's centrepiece will be the spectacular banquet in St George's Hall later on Wednesday, with speeches by King Charles and Trump and a menu that is likely to be a culinary representation of the special relationship, with UK and US food.

Such spectacles will be aimed at pleasing a president who has spoken of his enthusiasm for royalty - and alongside the pageantry and photo-opportunities, there will be efforts to influence the US president over trade and international co-operation.

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Trump sent positive signals ahead of his journey to the UK aboard Air Force One on Tuesday, calling the visit an"honour" and describing his "very good" relationship with the UK.

A multi-billion US technology investment deal was announced as the visit got under way - but Trump said the trip's main purpose was to see"my friend" King Charles.

"He represents the country so well, such an elegant gentleman," he said.

Trump and First Lady Melania received an official welcome on the runway at Stansted airport on Tuesday evening, by a line-up which included Foreign Secretary Yvette Cooper.

Starmer also held a short phone call with Trump late on Tuesday, to welcome him to the country.

The president spent the night in the US ambassador's London residence, Winfield House, where he again spoke fondly of the King:"He's been a friend of mine for a long time, and everybody respects him, and they love him."

Of the UK, Trump said:"I have a lot of things here that warm my heart. I want to tell you. It's a very special place."

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State visits are a form of soft power diplomacy, using the royal charm offensive to build relations with important international partners - with none more important than the US.

As the visit got under way, a major technology deal was announced with US tech firms investing £31bn in the UK, including £22bn from Microsoft.

This will see co-operation in artificial intelligence, quantum computing and nuclear power, in a tech deal which Sir Keir Starmer hopes will begin"creating highly skilled jobs, putting more money in people's pockets".

Trump had earlier said that the UK"want to see if they can refine the trade deal a little bit… I'm into helping them.

Ahead of the visit, the owner of Google, Alphabet, announced a £5bn ($6.8bn) investment in the UK's artificial intelligence research.

And an agreement is to be signed between the US and UK on accelerating the development of nuclear power.

But ambitions to remove the current 25% tariff on UK steel exports to the US seem to have been put on hold - although this remains lower than the 50% tariff facing many other countries.

Anti-Trump protestors begun to gather in Windsor on Tuesday - and giant images of Donald Trump and sex offender Jeffrey Epstein were projected on to the walls of Windsor Castle.

Thames Valley Police later said four men had been arrested following an"unauthorised projection" and remained in custody.

A heavy security operation will be in place during the presidential visit, which ends on Thursday afternoon.

But unlike other recent state visits, there will not be any moments visible to the public, with all the events taking place behind the walls of the Windsor estate or at the PM's country estate, Chequers.

The high street in Windsor has US flags flying, but they won't be seen by the visiting president.

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