LONDON — Britain’s capital is set to see tens of thousands gather on Saturday for what could be the largest far-right rally in decades, spearheaded by anti-immigration advocate Tommy Robinson.

The rally, titled “Unite the Kingdom,” emerges during a time of growing nationalism in the U.K., with a far-right political party gaining significant traction, and amid the backdrop of the murder of American conservative activist Charlie Kirk — an incident Robinson is using to rally supporters.

Robinson, whose actual name is Stephen Yaxley-Lennon, has consistently drawn crowds of predominantly white, male supporters who chant against Islam and immigration.

He promotes the event as Britain’s “largest free speech festival,” sharing video footage on X Saturday morning of large groups in central London proudly displaying England flags and British Union Jacks.

Anti-extremism group Hope Not Hate said it expected upward of 40,000 attendees.

Despite a history of “anti-Muslim rhetoric and instances of offensive chants by some participants in past marches,” British police have advised Muslim Londoners to proceed with their plans.

“Some have suggested that Muslim Londoners modify their activities this Saturday, including avoiding the city center,” stated Metropolitan Police Commander Clair Haynes, overseeing public order operations in London. “However, that is not our recommendation. Everyone should feel secure traveling to and within London.”

With five Premier League soccer matches taking place in the capital the same day, more than 1,600 officers will be deployed, police said.

“The football lads are coming from everywhere,” said Robinson, who was released from prison in May after being jailed for contempt of court in October.

In a video to supporters on Thursday about Kirk, who was shot and killed Wednesday while speaking at an event at a university in Utah, Robinson referred to “the bastard who has murdered him, or the organization, the corporation or the government it is that has killed him.”

“In honour of @charliekirk11 & in honour of freedom on the 13th we march,” he wrote in a separate post on X.

Hundreds of people gathered at a vigil in London on Friday night to mourn Kirk, 31, a father of two.

Steve Bannon, President Donald Trump’s former chief strategist, is listed to appear on stage at the rally on Saturday, along with right-wing commentator Joey Mannarino and a lawmaker from Germany’s far-right AfD party.

Canadian psychology professor Jordan Peterson is also in the lineup.

Robinson has told attendees not to wear masks, drink alcohol or be violent.

“It’s not a time for riots,” he said in a video on X. “It’s not a time for violence. It’s a time where you come and you stand proudly for your country.”

Britain’s far right has been emboldened as Reform UK, a party led by Trump ally Nigel Farage, tops the polls. Farage recently said he would deport 600,000 people if he wins the next election.

In recent months, English flags have increasingly appeared on lampposts, crosswalks and apartment windows — seen by some as patriotism and by others as linked to soccer hooliganism and racism.

A smaller counter-protest, organized by Stand Up to Racism, is also taking place in central London, led by leftist lawmakers Zarah Sultana and Diane Abbott.

Nearly 900 people were arrested under counterterrorism legislation at a London demonstration last weekend against the ban on the group Palestine Action, many of them older than 60.

The British government banned Palestine Action — which describes itself as a direct action movement that uses disruptive methods — as a terrorist organization in July, putting it alongside Al Qaeda and ISIS. Membership or support is now a criminal offense punishable by up to 14 years in prison.

That extends to acts such as wearing clothing, carrying items or holding placards that could reasonably be seen as showing affiliation with the group.