The mobilisation of around 15,000 far-right supporters in London for the imprisoned Tommy Robinson has been a wake-up call for many on the left.

The intention of Saturday’s march was clear — to normalise and spread the most vitriolic anti-Muslim hatred and to build a new far-right movement based on the growth of anti-Muslim groups across Europe.

The event received international support from the far right and fascists. Geert Wilders, leader of the Dutch Party for Freedom and Belgian fascist Vlaams Belang member Filip Dewinter, who was guest speaker for a gathering of the former SS-collaborators of Sint-Maartensfonds (Belgium) in 2001, addressed the demonstration.

Other speakers included Ukip leader Gerard Batten, ex-Ukip member now leader of For Britain Anne Marie Waters and Raheem Kassam.

Kassam was former editor-in-chief of Breitbart News London, chief adviser to ex-Ukip leader Nigel Farage and marketing director of the Henry Jackson Society.

Kassam organised the event in an alliance with ex-EDL members such as Kevin Carroll and Ukip and they were supported by Steve Bannon. Journalist Natalie Nougayrede recently described Bannon’s strategy as “on a far-right mission to radicalise Europe.”

The Democratic Football Lads Alliance mobilised football hooligan “firms” to the demonstration. The event also attracted ex-British National Party and National Front fascists, and many raised their arms in nazi salutes. Tourists and police were violently attacked.

Forces to the right of the Conservative Party, from Ukip to fascists, backed by the international alt-right, united under the “Free Tommy Robinson” slogan.

This potentially paves the way for an alt-right, populist movement in Britain. To halt this far-right street movement, one has to understand why it is emerging. There are several reasons.

First this movement is a product of the normalisation of Islamophobia. Mainstream politicians and political parties often concede to pernicious myths. In particular that mainstream Islam and Muslims are responsible for terrorism and the rape, sexual abuse and exploitation of white girls.

This is the cutting edge of large far-right demonstrations and these myths must be dispelled.

Terrorism must be condemned and rooted out of society. Laying responsibility at the doorstep of the Muslim population as a whole will only sow division, not prevent terrorism.

When Theresa May stood on the steps on Downing Street after the London Bridge attacks in 2017 and said there was far too much “tolerance of extremism” and referred to “separated, segregated communities,” she was targeting the Muslim population. This strengthens myths peddled by the far right and will lead to its growth, not defeat it.

Robinson’s imprisonment for contempt of court during a “grooming” trial in Leeds, led to a far-right racist reaction. Our movement must properly address the grooming issue.

The sexual abuse and exploitation of women and children and the historic failure of those responsible to properly tackle the crime and bring the perpetrators to justice must be condemned. We must support and seek justice for all victims of sexual exploitation regardless of their social or ethnic background. We must condemn and seek prosecution of all those responsible for these crimes irrespective of their ethnicity or creed.

Those who seek to present this as a crime committed by only Muslim or Pakistani men targeting white girls, must be challenged. The 2014 Independent Inquiry into Child Sex Exploitation in Rotherham by Alexis Jay OBE revealed that “there is no simple link between race and child sex exploitation.”

The report reminded us of the conclusions reached by the Deputy Children’s Commissioner that “one of these myths was that only white girls are victims of sexual exploitation by Asian or Muslim males, as if these men only abuse outside of their own community, driven by hatred and contempt for white females. This belief flies in the face of evidence that shows that those who violate children are most likely to target those who are closest to them and most easily accessible.”

Second, the Robinson far-right street movement is a product of a decade of economic stagnation and a fall in living standards for the majority of the population. Instead of providing a solution to this, the Tory government is exacerbating the problem with austerity, using racism and Islamophobia to scapegoat immigrants, Muslims, refugees and distract people from its failure. This is what led to Brexit and has created fertile ground for the far right.

Thirdly, this movement is a counter-movement to the strength of the left and the anti-racist movement. Jeremy Corbyn’s leadership of the Labour Party represents opposition to austerity and racism — the precise antidote needed at this time. It polled over 40 per cent in the 2017 general election under difficult circumstances.

Momentum and many trade unions have organised a pro-Corbyn grassroots movement on the ground.

This was reflected in activists turning out the vote in elections, but also the huge rallies in support of Corbyn prior to the general election.

In addition 100,000 mobilised in defence of refugees in 2015. Tens of thousands mobilised against Donald Trump’s Muslim ban in 2017. From 2014 to 2018 between 10,000 and 30,000 people have mobilised for demonstrations marking UN Anti-Racism Day.

Huge mobilisations for Corbyn and against racism have inevitably sent shock waves through the right and led to a counter-movement to the far right.

The lesson of history is that we must unite against racism and fascism. The obvious target is Muslims. However Muslims are not the only people in the line of fire. Darren Osborne, the Finsbury Park terrorist who attacked Muslims, revealed in court he wanted to kill Corbyn. Jo Cox was murdered by a fascist. This illustrates the threat the far right poses to the Labour Party and trade unions.

In Leeds around 400 people marched, shouting support for Robinson and “Get the Muslims out.” This toxic atmosphere led to attacks on a mosque and gurdwara (Sikh temple) later that week.

The far right is a threat to the whole labour movement, as well as Muslims, Jews, Sikhs, Hindus, African, Caribbean, LGBT people, all progressives and anti-racists.

We must mobilise the biggest, broadest demonstration against Trump’s visit on Friday July 13, which rejects the racism and Islamophobia of the alt-right.

Robinson supporters will be using Trump’s visit to galvanise the far right the following day. Allowing them to march unopposed would mean that movement grows unopposed.

Counter-mobilisations against the far right are correct. Those horrified by the “Free Tommy Robinson” demonstration must join this counter-demonstration on Saturday July 14.

We must defend Corbyn’s anti-austerity and anti-racist leadership of the Labour Party. We must also build Stand up to Racism and Unite Against Fascism and counter racist myths peddled by the right.

Sabby Dhalu is Unite Against Fascism joint secretary and Stand up to Racism co-convener.