The statue of Winston Churchill was barricaded off as thousands of supporters of far-Right activist Tommy Robinson marched through central London.
Police mounted a major operation on Saturday as anti-racist counter-protesters began to march nearby in even larger numbers to oppose the far Right.
Robinson, 41, whose real name is Stephen Yaxley-Lennon, had called on his supporters to gather for what they described as a “Uniting the Kingdom” march.
The protest set off from Victoria station, heading to the southern end of Whitehall, while the counter-protest began near Piccadilly Circus and was heading towards the north end of Whitehall.
Churchill’s statue in Parliament Square was protected by a ring of steel barriers and the Cenotaph on Whitehall was protected by metal hoardings.
The self-proclaimed anti-Islam campaigner missed his own planned protest after he was remanded into custody on Friday, charged with failing to provide his mobile phone access code to the police under schedule seven of the Terrorism Act 2000, Kent Police said.
Robinson is separately due to appear at Woolwich Crown Court on Monday for a two-day hearing concerning allegations that he breached a 2021 High Court order barring him from repeating libellous allegations against a Syrian refugee who successfully sued him.
It is understood the airing of a film titled Silenced at the Trafalgar Square demonstration is one of six actions alleged to have breached the injunction between June and July.
Some in the crowd carried banners demanding the release of Robinson from custody while others flew Union flags.
A huge banner, proclaiming “The Rape of Britain”, was held aloft next to photographs of Sadiq Khan, the mayor of London, Rishi Sunak, the former prime minister and Sir Keir Starmer.
Chants of “Oh Tommy, Tommy” and “We want Starmer out” were heard as the march made its way along Victoria Street to Parliament Square.
Tens of thousands of counter-protesters gathered to oppose the Robinson march after Stand Up to Racism called on people to “take to the streets” in a “massive anti-fascist demonstration”.
Trade unionists, community groups and activists descended on the capital by coach and train for what was described as one of the biggest anti-fascist mobilisations in decades.
Dozens of trade union banners could be seen among the crowds, including the National Education Union, the RMT and the Fire Brigades Union. Others held placards reading ‘Stop the Far Right’ and ‘No to Islamophobia’.
Among those addressing the anti-racist marchers as they assembled at Piccadilly was historian Louise Raw.
The Met said static rallies were expected at the end of both marches.
Hundreds of Metropolitan Police and British Transport Police officers were joined by officers from other forces across the country to ensure the two sides were kept apart.
In July, as many as 20,000 supporters of Robinson staged a march in central London, with claims of Islamophobic and racist chants among the crowd.
Robinson was a member of the far-Right British National Party and founded the English Defence League.