Boris Johnson joined tens of thousands of protesters at a march against anti-Semitism, where far-right figurehead Tommy Robinson was escorted away by police.
The former Prime Minister and his wife Carrie, carrying their young son Frank, attended the demonstration in London, which comes a day after a massive pro-Palestinian rally demanding a ceasefire in Gaza.
Organisers from the Campaign Against Anti-Semitism had said Mr Robinson, 40, a former leader of the English Defence League, and his far-right thugs were not welcome at the demo. He was spotted amongst counter protesters who clashed with police during ceasefire protests held on Armistice Day.
Mr Robinson was seen having a full English breakfast in the Soho coffee shop opposite the Royal Courts of Justice, near the start point of the protest. He was escorted away from the march by police officers.
The Metropolitan Police later revealed that a 40-year-old man who refused to leave the area had been arrested. The force said in a statement: "He was spoken to and warned on more than one occasion that his continued presence in the area was likely to cause harassment, alarm and distress to others. He was directed to leave the area but refused to do so."
Another man was also arrested on suspicion of a racially aggravated offence as crowds left Whitehall, the force said.
Organisers said it was the largest rally against anti-Semitism in the capital since the Battle of Cable Street in 1936, when hundreds of thousands of people blocked a planned march by Oswald Mosley's British Union of Fascists through an area populated by Jewish families.
Mr Johnson compared anti-Semitism to "an old spore of a virus" that had flared up. He said: "We need to remember that and whatever the whatever the rights and wrongs of what Israel has done, or is doing, I think that the anti-Semitism that we've seen in some of these marches around Western Europe and further afield has really confirmed for me the absolute necessity, the human necessity, for Israel to exist."
Chief Rabbi Sir Ephraim Mirvis told crowds there had been an "alarming" rise in anti-Jewish sentiment since the October 7 attacks by Hamas. But he vowed: "We will not be intimidated."
Immigration minister Robert Jenrick and security minister Tom Tugendhat were among the well-known faces, including Tracy-Ann Oberman, Rachel Riley and Rob Rinder at the march. Mr Jenrick, who said he was at the march to represent the Government, spoke from the stage to warn that "enough is enough". He said anti-Semitism was a "stain on our country, it is moral decay".