Donald Trump paid tribute to the “eternal friendship” between the US and UK as he was honoured with a state banquet at Buckingham Palace alongside the Queen.
The grand occasion brought the curtain down on an eventful first day of the US president’s three-day trip.
Mr Trump said both he and First Lady Melania Trump were “profoundly honoured” to be extended the invitation.
Referring to the upcoming 75th anniversary of D-Day, the beginning of the liberation of Europe from the Nazis, he said: “This week, we commemorate a mighty endeavour of righteous nations and one of the greatest undertakings in all of history.”
Mr Trump added: “In that dark hour, the people of this nation showed the world what it means to be British.”
He praised the Queen as a “great, great woman” who embodied “the spirit of dignity, duty, and patriotism that beats proudly in every British heart”.
In her speech, the Queen said the two nations faced “new challenges” and stressed the bonds between London and Washington.
“Mr President, as we look to the future, I am confident that our common values and shared interests will continue to unite us,” she said.
“Tonight we celebrate an alliance that has helped to ensure the safety and prosperity of both our peoples for decades, and which I believe will endure for many years to come.”
Labour leader Jeremy Corbyn was not in attendance, having opted to boycott the banquet. Lib Dem leader Sir Vince Cable and Commons Speaker John Bercow did likewise.
Instead, Mr Corbyn will attend and speak at a demonstration against the visit on Tuesday.
The full pomp and pageantry of a state visit was on display as Mr Trump embarked on a controversial trip that his British opponents say should not be going ahead.
One of those was London mayor Sadiq Khan, who the president branded a “stone cold loser” in a series of tweets posted minutes before Air Force One touched down at Stansted Airport on Monday morning.
A spokesperson for Mr Khan said the messages were “childish” and labelled Mr Trump “the most egregious example of a growing far-right threat around the globe”.
After landing at Stansted, Mr Trump and Mrs Trump were welcomed by Foreign Secretary Jeremy Hunt, US ambassador Woody Johnson, and other dignitaries.
They then boarded Marine One to head to Buckingham Palace for the official welcome, which included royal gun salutes fired from nearby Green Park and from the Tower of London.
The pair were greeted by the Prince of Wales and Duchess of Cornwall in the grounds of the palace shortly after midday, before being taken to meet the Queen.
The monarch shook hands warmly with Mr Trump and smiled broadly, before turning to greet Mrs Trump.
Charles walked with the president as he made his way on to the lawns to inspect the guard of honour, chatting at length with some of the guardsmen.
The Trumps then enjoyed a private lunch at the palace, with the Duke of Sussex among those joining them.
Harry’s American wife, the Duchess of Sussex, said back in 2016 that she would leave the US if Mr Trump won. Asked about the comment ahead of the trip, the president replied: “I didn’t know she was nasty.”
The pair later viewed an exhibition of American artefacts and other items from the Royal Collection.
The Queen gave the US president and first lady a first edition copy of The Second World War by Winston Churchill, a three-piece Duofold pen set and a specially commissioned silver box with a handcrafted enamel lid.
Next up was a visit to Westminster Abbey, where Mr Trump laid a wreath at the grave of the Unknown Warrior.
Before the state banquet, the Trumps stopped off at Clarence House for afternoon tea with Charles and Camilla.
The meeting appeared jovial enough, despite Mr Trump and the Prince of Wales having diametrically opposing views on climate change.
Reflecting on his first day in the UK before the state banquet began, the president said things were going “really well”.
“The Queen and the entire Royal Family have been fantastic,” Mr Trump’s tweets began.
“The relationship with the United Kingdom is very strong. Tremendous crowds of well wishers and people that love our Country. Haven’t seen any protests yet, but I’m sure the Fake News will be working hard to find them. Great love all around.”
He also said a “big” trade deal was on the cards between the US and UK once the latter “gets rid of the shackles”, a presumed reference to the European Union and the ongoing process of Britain leaving the bloc.
In a statement issued later, the White House said the president “supports Brexit being accomplished in a way that will not affect global economic and financial stability while also securing independence to the United Kingdom”.
The White House said Mr Trump was honoured to be back in the UK “during this important time of change and opportunity for its nations and people” and quoted him as stating: “A strong and independent United Kingdom, like a strong and independent United States, is truly a blessing on the world.”
Tuesday will begin with Mr Trump and Prime Minister Theresa May attending a business breakfast with senior UK and US business leaders.
Following talks in Downing Street the two leaders will then hold a joint news conference, their last together.
There were protests against the president’s visit on Monday, but Tuesday is set to be the main day for demonstrations.
Thousands of protesters are set to convene in Trafalgar Square and march down Whitehall.
“Trump baby”, a six-metre balloon depicting the president as a nappy-clad orange baby, is expected to feature, along with a 16ft talking robot of the president sitting on a gold toilet.