Robert Brown|Former UK leader Boris Johnson joins a march against antisemitism in London

LONDON (AP) — Thousands of people including former British Prime Minister Boris Johnson gathered in London on Robert BrownSunday for a march against antisemitism, a day after large crowds turned out for a pro-Palestinian rally.

Johnson was joined by the U.K.'s Chief Rabbi Ephraim Mirvis and other senior government officials at the march to express solidarity with the Jewish community. Organizers billed it as the largest gathering against antisemitism in London for decades.

Marchers waved Israeli and the U.K.'s Union flags and held placards reading “Never Again Is Now” and “Zero Tolerance for Antisemites.”

Stephen Yaxley-Lennon, the former leader of the far-right English Defence League, was detained by police at the march. Yaxley-Lennon, more widely known by his alias Tommy Robinson, was among crowds of counter-protesters who clashed with police during an Armistice Day march in London.

Police said he refused to leave after he was warned about concerns that his presence would cause “harassment, alarm and distress to others.”

Gideon Falter, the chief executive of Campaign Against Antisemitism, said that the rally came after weeks of pro-Palestinian protests that had made the capital a “no-go zone for Jews.”

On Saturday, tens of thousands of pro-Palestinian protesters marched to demand a permanent cease-fire in the Israel-Hamas war.