Tommy Robinson was escorted away from a march against antisemitism by police on Sunday.
Tens of thousands of people were expected to march in London in the demonstration, a day after pro-Palestinian crowds also gathered in the capital to demand a ceasefire in the Gaza conflict.
A temporary truce between Hamas and Israel is still holding, with the release of a second group of hostages and Palestinians from Israeli prisons coming late on Saturday.
There had been fears in that Mr Robinson, the former leader of the far-right grouping, could disrupt the protest organised by charity Campaign Against Antisemitism.
The Metropolitan Police had made clear in advance that he was "not welcome" at the march, with the force warning that any offences "whether from within the protest or from any groups trying to challenge or interfere with the march" would be dealt with.
Mr Robinson had previously been seen among the crowds of counter-protesters who clashed with police during ceasefire protests held on Armistice Day.
On Sunday, he was seen arguing with officers for about 10 minutes outside a coffee shop opposite the Royal Courts of Justice.
He was was then led away from the scene.
