“RAPE-GANG members are predominantly followers of the cult of Mohammed,” declares the speaker, in a matter-of-fact tone. The crowd gathered on Whitehall boo. “The founder of their cult was himself a paedophile and kept sex slaves,” he continues in a near monotone. MPs are “traitors, collaborators and quislings,” he adds. “They must be swept away.” The language was incendiary, the delivery was prosaic and the messenger was Gerard Batten, the leader of the UK Independence Party.

UKIP is back. After weeks of headlines and government resignations over the Conservatives’ bungled negotiations to leave the European Union, the party that infected British politics with the Brexit virus is on the up. Polls put UKIP at up to 8%, the same as the Liberal Democrats. A narrative of betrayal is driving voters back to UKIP. But they are returning to a very different party to the one they left.

Britain’s radical right is undergoing an evolution. Mr Batten was speaking at a rally demanding the release of Tommy Robinson, the founder of the English Defence League, an Islamophobic protest movement. Mr Robinson was jailed for 13 months in May for contempt of court, after he filmed defendants entering court during a trial that was subject to reporting restrictions and broadcast the result to his then 800,000-strong army of Facebook followers. Under Nigel Farage, its previous leader, UKIP built a firewall between the party and the far right. Under current management, the lines between UKIP and its more unpleasant cousins are blurred. Mr Batten has made support for Mr Robinson a key plank of his leadership platform. David Kurten, a member of the London Assembly for UKIP, sums up the party’s evolution: “Nigel was Mr Brexit. Now we are looking at a broader cultural agenda.”

Until now, Britain has been lucky in its radical parties, argues Rob Ford of the University of Manchester. Under Mr Farage, UKIP focused on Brussels and blanched at outright Islamophobia, in contrast to the likes of Geert Wilders in the Netherlands. The relative scarcity of explicit anti-Muslim sentiment in British party politics is down to a want of supply rather than lack of demand. British voters are no more tolerant of Muslims than most of their European peers. Some 42% of Britons say that Islam is fundamentally incompatible with their country’s values, bang on the European median, according to Pew Research. The new UKIP has few qualms about speaking for this large minority.

There is complacency about extremism in British politics. The murder of Jo Cox, a Labour MP, by a neo-Nazi fanatic in 2016, is painted by some MPs as an isolated tragedy. A far-right plot to kill another Labour MP in 2017 attracted surprisingly little attention when it was unearthed. Meanwhile, those on the fringes of political discourse are given reams of coverage. On July 15th Mr Farage used his LBC radio show to broadcast a chummy interview with Stephen Bannon, a former adviser to Donald Trump and godfather to the American alt-right, who argued that Mr Robinson should be released.

Mr Robinson has become a cause célèbre for far-right activists across Europe and in America. UKIP is attempting to ride this wave of online support for him. Earlier this summer a gang of YouTubers sympathetic to Mr Robinson publicly joined the party. They include Paul Joseph Watson, a YouTuber with 1.3m subscribers and presenter on the conspiracy website Infowars. For a party that will lose its 18 MEPs when Britain leaves the EU, a new way to generate attention may come in useful.

The arrival of the YouTubers coincided with about 1,000 people joining in June, according to sources in the party. But double that number have joined so far in July, as the government’s Brexit plan has fallen apart. Those who backed UKIP in 2015, when it won 4m votes in the general election, but switched to the Tories in 2017, are returning, says Mike Hookem, a UKIP MEP. People leaving the Conservatives and returning to the UKIP fold may not know quite what they have signed up for.