They made as much din as they could outside the US Ambassador’s residence, Winfield House in Regent’s Park where the President and his wife Melania were due to sleep after dining with Theresa May at Blenheim Palace in Oxfordshire.
But the vuvuzela-blowing campaigners who were banging pots and pans along with drums, were kept well away as tight security was put in place.
Twelve-foot high metal barriers have been erected, areas of the park were closed off and mounted police were patrolling the site to prevent trouble.
The first protesters started arriving at the park at around 5pm and jeered at the number of helicopters arriving at Winfield House carrying the Presidential party.
Mini buses with blacked out windows were seen heading into the grounds of the residence early in the evening and were understood to be carrying guests to meet Mr Trump and the First Lady before they flew to Blenheim.
There was a mixed response as some passing motorists told the demonstrators, congregating in a fenced-off area near the Regent’s Park Mosque, to go home.
Others gave friendly toots as placards were brandished saying “Special Relationship? Just Say No” and “No to Trump, No to War”.
Campaigner Sarah Wrack, 29, said: “I’m in solidarity with all the people in the US who oppose him and many do, especially young people. He’s very dangerous.
“I’ve heard people say we should ignore him or were being disrespectful.
“We don’t disrespect the American people – but we must protest.”
Others in the capital hung a large banner attacking Mr Trump from the side of Vauxhall Bridge.
More people are expected to turn out for the protests at Trafalgar Square this afternoon and in other cities.
Helen Pattison, 27, a teacher from East London, is taking teenage school pupils with her to the square after staging a class walkout.
She said: “We have not just a right to protest but a duty.”
Her brother Ian, 29, said: “I can’t just stand by and ignore him. He’ll do what he wants anyway, but at least this way he’ll know people won’t be quiet.”
Mr Trump is the 12th sitting US president to visit Britain.
Venues for his three-day trip have largely been chosen away from the capital for fears of protests.