Amnesty International hung a 50 foot-long banner emblazoned with the words "Human Rights Nightmare" and a large image of Trump on a bridge close to the new US embassy. He says it "must ultimately" go to 4 percent.
A large "Human Rights Nightmare" banner has been unfurled by Amnesty International activists across the river Thames on Vauxhall Bridge to protest against the visit.
"Mr President, Sir Winston Churchill once said that, "To have the United States at our side was, to me, the greatest joy", Ms May told Mr Trump, according to a text of her speech provided by her office.
"[Until] I remember her desperate rush to invite him, her repeated reluctance to criticise his Muslim ban or caging of children, her chasing him for a bad trade deal".
A high fence has been erected around the USA ambassador's central London residence where Trump will spend Thursday night and the embassy has sent out an alert warning Americans in London to keep a low profile in case protests turn violent. "I get along with her very nicely".
The Trumps arrived Thursday evening for a black-tie dinner.
"I partially won an election because of immigration", he said, also pointing to Italy's recent vote, in which Giuseppe Conte took government after campaigning on a populist anti-immigration platform.
Mr Trump said the UK/US relationship was the "highest level of special" and both made much of our mutual trading levels.
"The people voted to break it up (Britain's ties with the EU)", Trump said in Brussels following a North Atlantic Treaty Organisation summit there just before flying to London. "But when they make you feel unwelcome, why would I stay there?"
Late a year ago, Ms May herself criticised Mr Trump for retweeting a message by a member of a British far-right group, and the speaker of parliament has said the president would not be welcome to address the chamber.
Many Conservative members of Parliament who support Brexit are already in open revolt over her proposals, which Johnson said would turn the United Kingdom into an European Union "colony" - and Trump's remarks are sure to inflame their concerns. And past year Trump was critisied across the political spectrum for deriding London's mayor's response to an Islamist attack.
Britain and the USA are the largest investors in each other's economies, with over a trillion dollars of investments between them, Mrs May, said, adding: "The strength and breadth of Britain's contribution to the United States economy can not be understated". I think the immigration, allowing the immigration to take place in Europe is a shame.
The president is set to largely avoid mass protests planned for his controversial trip, which includes talks with May, tea with Queen Elizabeth II and a private weekend in Scotland. According to his itinerary, the USA president will mostly stay away from London to avoid embarrassing protests.
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.