US President Donald Trump has kicked off his historic second state visit to Britain with unprecedented pomp, intense security and protests.

Trump and wife Melania took their seats at a lavish banquet at Windsor Castle on Thursday morning (AEST) after a full day of pageantry and ceremonies.

The guest list for the posh dinner was noticeably absent of celebrities, but included industry heavyweights such as media mogul Rupert Murdoch and Apple CEO Tim Cook.

The King speaks as Trump and the Princess of Wales listen during the state banquet. Photo: AAP

The King delivered a speech in St George’s Hall at Windsor Castle, highlighting the friendship between Britain and US some 250 years after American independence.

“We celebrate a relationship between our two countries that surely neither Washington nor King George III could possibly have imagined,” he said.

“The ocean may still divide us, but in so many other ways we are now the closest of kin.”

The French-written menu reportedly included organic Norfolk chicken ballotine wrapped in zucchinis with a thyme and savoury infused jus, followed by dessert of vanilla ice-cream bombe with Kentish raspberry sorbet and lightly poached Victoria plums.

A view of 160 guests at the state banquet at Windsor Castle. Photo: AAP

The Trumps were earlier greeted, after landing on British soil, by the Prince and Princess of Wales and then welcomed by the King and Queen.

Their first day included the largest military ceremonial welcome for a state visit in living memory.

Trump and his wife then took part in a carriage procession and a flypast of the Red Arrows (Royal Air Force aerial team). They also visited the late Queen Elizabeth’s tomb at St George’s Chapel.

At one point during the day, while the King and Trump inspected a Guard of Honour, they shared a chuckle when the monarch jokingly advised the President to “watch the sword”.

The Prince and Princess of Wales receive Trump and US first lady Melania. Photo: AAP

Meanwhile, thousands of protesters took to the streets of central London for largely peaceful demonstrations against the visit. Other causes were also represented, including Palestine and climate change.

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

“It’s a very special place,” he said, adding that he loved the UK.

British Prime Minister Keir Starmer is hoping to use that sentiment to the country’s advantage as his government seeks to use the trip to cement “special relationship” with the US, deepen economic ties, secure billions of dollars of investment, discuss tariffs and press Trump on Ukraine and Israel.

Trump inspects a guard. Photo: AAP

Companies including Microsoft, Nvidia, Google and OpenAI have already pledged £31 billion ($63 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 British secured an initial deal with Trump to lower some tariffs.

“They want to see if they can refine the trade deal a little bit,” Trump said on Tuesday.

But while Starmer is banking on the royals to help cajole the Anglophile President, whose mother came from Scotland, many pitfalls remain.

A ‘Stop Trump Coalition’ demonstration against the state visit. Photo: AAP

Polls suggest Trump is 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.

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

Last week, Starmer sacked Peter Mandelson as the UK ambassador to Washington DC over his ties to Epstein, which could lead to questions for both Starmer and Trump, whose own relationship with the financier has become an issue.

While there was a massive security operation in Windsor, British police said four people were arrested on Tuesday after images of Trump alongside Epstein were projected onto one of the castle’s towers.

Trump was not there at the time.

Crowds of Trump supporters gathered in Windsor but in London thousands marched to protest against the state visit.

“I quite simply dislike everything that Trump and his administration represent around the globe,” retiree Bryan Murray said.

Trump and his wife joined the King and Queen and other royals and dignitaries for a carriage procession on Wednesday, with the route lined by 1300 British service personnel.

Trump, occasionally chatting and smiling with the King, then inspected a guard of soldiers who wore scarlet uniforms and bearskin hats.

Later, the Trumps viewed historical items from the Royal Collection relating to the US.

Trump was shown a letter sent from US president Abraham Lincoln to Queen Victoria in 1862 expressing condolences after the death of Prince Albert, which was described as a “defining moment” in the special relationship between Britain and the US.

Trump remarked “that is so amazing, that’s the real deal” and leant forward to have a closer look.

He and his wife then visited St George’s Chapel, the final resting place of Queen Elizabeth, who hosted Trump for his first state visit in 2019, to lay a wreath on her tomb.

She died in September 2022.

There was a further military parade and a flypast by Britain’s Red Arrows aerobatics team.

The Trumps also found time for a private meeting with the King’s “very handsome” – as Trump has called him – eldest son Prince William and wife Kate. It was described by the prince’s spokesperson as “warm and friendly”.

-with PA/AAP