London, United Kingdom – Hundreds of thousands of people have marched through central London in what organisers are calling the largest ever demonstration against the far right in British history.

The Together Alliance march, backed by about 500 groups including trade unions, antiracism campaigners and Muslim representative bodies, brought together a diverse crowd of all ages from across the country on Saturday, converging on Whitehall near the Houses of Parliament.

Organisers said that half a million people took part.

Kevin Courtney, chairman of the Together Alliance, told crowds the march “gives us all confidence to carry on.”

London’s Metropolitan Police put the figure considerably lower, at approximately 50,000, though officers acknowledged it was difficult to reach an accurate figure given how spread out the crowds were.

The protest was met with a far smaller group of counterprotesters waving Israeli flags and Iran’s pre-1979 monarchical flag.

Aadam Muuse, a trade union activist, told Al Jazeera that racism and Islamophobia had moved from the fringes into mainstream politics, and was “being pushed by parliamentarians”.

He said the march was “much needed to push back against [Reform leader Nigel] Farage and his ilk,” adding that the party “must be defeated at the ballot box”.

Al Jazeera’s Milena Veselinovic, reporting from the march, said demonstrators were pushing back against what they saw as “the politics of hate and division” in the United Kingdom.

One demonstrator, activist and writer Hamja Ahsan, told Al Jazeera he was motivated to attend after a rally organised by the far-right agitator-activist Tommy Robinson that drew 150,000 people and was marred by violence that injured several police officers. Robinson is reportedly planning another rally in May.

“We need to show them that we’re the majority,” Ahsan said. “At a street level, the far right won’t take over our streets.”

He said the atmosphere on Saturday was akin to the Notting Hill Carnival, as the march united people from all backgrounds, “from pensioners to children”.

Museum worker Charlotte Elliston told Al Jazeera that she also feels unsettled by the far right’s creeping rise.

“You think this would never happen here, and then all of a sudden this might happen,” she said. “You see that it is getting scary.”

Several left-wing politicians joined the demonstration.

Independent MP Jeremy Corbyn posted on X that the “problems we face are not caused by migrants or refugees”, arguing they were rooted instead in “an economic system rigged in favour of corporations and billionaires”.

MP Zarah Sultana said on X, “There’s one minority we should be angry at: the billionaires funding division while working class people can’t make ends meet.”

Green Party leader Zack Polanski, Dianne Abbott and Greater Manchester mayor Andy Burnham were also among the crowds.

‘Historic demonstration’

The rights group Amnesty UK hailed the “historic demonstration”, saying marchers were “calling for a different vision of society – one which places dignity, compassion and human rights at its heart”.

A separate march organised by the Palestine Solidarity Campaign, which assembled at Exhibition Road near Hyde Park, converged with the main demonstration during the afternoon.

Eighteen people were arrested outside New Scotland Yard on Saturday after staging a protest in support of Palestine Action, the protest group which remains proscribed under the Terrorism Act despite a High Court ruling in February that the government’s decision to ban it was unlawful.

The march comes amid rising racism as Farage’s Reform party surges in the polls.

Hope Not Hate, an antiracism campaign group, warned earlier in March that the British far right is now “bigger, bolder and more extreme than ever before”.