Following the gala event at the 18th century country house, Trump and his wife will come to central London to spend a night at US Ambassador Woody Johnson's official London residence, Winfield House, in Regent's Park. She praised the friendship between the two allies, glossing over Trump's previous remarks that Britain was a "hot spot" in turmoil over Brexit.
Trump arrived around 1:45 p.m. Thursday, straight from the North Atlantic Treaty Organisation summit. Two senior ministers resigned in protest this week at her plans for trade with the European Union after Britain leaves the bloc next March. The people voted to break it up so I would imagine that's what they'll do but maybe they are taking a little bit of a different route, so I don't know if that's what they voted for.
"Our trade and investment relationship is unrivalled - we are the largest investors in each other's economies and every day a million British people go to work for U.S. companies in the United Kingdom and a million Americans go to work for United Kingdom companies in the U.S.", May said.
Asked about Trump's comments at a hastily-arranged meeting with journalists, May said she was delivering wishes of the British people.
A trade deal with the United States is one of the main aims of Brexit supporters within May's Conservative Party, who are concerned that she is making too many concessions to the EU.
Trump has always been a Brexit supporter and has expressed enthusiasm for a wide-ranging trade deal with Britain after Brexit, something heralded by eurosceptics as being one of the great benefits of exiting the bloc.
That turmoil includes the resignations of May's Brexit and foreign ministers over her plan to retain close ties with the European Union after leaving the bloc in March.
Donald Trump meets with Theresa May.
However, despite the welcome from May, many Britons remain deeply opposed to Trump's visit.
Some 77 percent of Britons have an unfavorable view of Trump, according to a poll by YouGov with 1,648 respondents. "I think that's why Brexit happened".
They also touched upon post-Brexit trade.
"The United States commitment to North Atlantic Treaty Organisation is very strong", he said.
Police expect more than 100,000 protesters.
The U.S. Embassy has warned U.S. citizens to keep a low profile during the visit because of the protests, the sort of warning usually issued in more volatile locations.
Protesters are set to fly the Baby Trump blimp over Parliament on Friday when Trump will not be in town.
A campaign is also underway to get "American Idiot", a 2004 song by the USA punk rock band Green Day, to the top of the UK Singles Chart.
It is not simply the protesters, who are expected to dog Trump throughout his visit, including his weekend in Scotland, but his fraught relationship with political leaders accustomed to harmonious exchanges with US leaders, a tradition of unity that goes back at least to the vital World War II partnership of Franklin D. Roosevelt and Winston Churchill.
Mr. Trump landed in London on Thursday afternoon for a four-day visit that includes tea with the Queen at Windsor Palace, a black-tie dinner at Winston Churchill's birthplace and a few rounds of golf in Scotland.
On Friday, May and Trump will hold talks on Brexit, relations with Russian Federation, and trade ties at the prime minister's Chequers country residence, followed by a press conference.