Protesters are staging a noisy gathering near Winfield House where Donald Trump and his wife Melania are to spend the night.
A large group of demonstrators adopted an alternative version of England’s World Cup anthem Three Lions as they sang and shouted, “He’s going home, he’s going home, he’s going, Trump is going home” in Regent’s Park.
A wide range of campaigners, including unions, faith and environmental groups came together to unite in opposition to Mr Trump’s visit to the UK, organisers said.
Bells and whistles rang out alongside cheers and claps for speakers throughout the protest, staged near the US ambassador’s official residence, as the crowd was encouraged to shout loudly in the hope Mr Trump could hear.
Placards including “Dump Trump” and “Trump not welcome” were held aloft by the enthusiastic crowd before some began banging on the metal fence which has been erected in the park.
A clip of what organisers said was the sound of children crying at the US border after being separated from their parents was played and described by those listening as “disgusting”.
Sam Fullerton from Oklahoma said while Mr Trump may not see the protest from Winfield House which is set back inside the fenced-off area in the park, he hoped he would hear it or see it on television.
Mr Fullerton said: “He watches a lot of TV so he’ll see it on TV. Or they may be out in the backyard.”
His wife Jami, a Hillary Clinton supporter, said the protest was “democracy at its finest”.
“I’m here to witness democracy outside of our own country to see how other democratic societies express themselves,” she said.
“I think it’s great. The British are pretty gentle people.”
John Rees, of the Stop The War group, described Mr Trump as a “wrecking ball” as he addressed those gathered.
He said: “He’s a wrecking ball for race relations, he’s a wrecking ball for prosperity, he’s a wrecking ball for women’s rights, he’s a wrecking ball for any peace and justice in this world and we have to stop him.”
Some of those gathered said they planned to stay for Mr Trump’s return after the First Couple dine at Blenheim Palace with Theresa May.