In his paper on how the far right became part of the mainstream, the academic Joe Mulhall said far-right demonstrations had grown to sizes not seen since the 1930s.

The “Free Tommy [Robinson]” event in August, the “Day of freedom” march in May and the “Brexit betrayal” demonstration in December all attracted large numbers of people.

“With such large numbers hitting the streets, many have asked whether the far right has now become acceptable and perhaps entered the mainstream in the UK,” wrote Mulhall, a researcher with the anti-racism group Hope not Hate, in the paper published last month for the Commission for Countering Extremism.

The assault against the Guardian columnist Owen Jones left him asking the same question. “I’m just a symptom of a wider phenomenon, an emboldened, increasingly violent far right,” said Jones.

All the official evidence suggests far-right violence is on the rise across the UK.

At least four far-right terror plots were foiled by the police and security services last year and, for the first time, the threat from extreme rightwing and leftwing terrorism will be reflected in the official threat level.

The system previously described the threat from “international terrorism”, which has become largely synonymous with Islamist terror.

Both the head of UK counter-terrorism policing, Neil Basu, and the director general of MI5, Andrew Parker, have warned far-right criminality is on the rise.

Police forces do not record “far-right” incidents but they do record terror-related offences and hate crime, the latter of which has risen sharply.

The most recent official statistics on hate crime show that in 2017-18, there were 94,098 hate crime offences recorded by police in England and Wales, an increase of 17% compared with the previous year.

Of these, 71,251 or 76% were race hate crimes, 11,638 or 12% were sexual orientation hate crimes, 8,336 or 9% were religious hate crimes, 7,226 or 8% were disability hate crimes and 1,651 or 2% were transgender hate crimes.

The Home Office said the increase was largely driven by improvements in police recording, although there were spikes in hate crime following the EU referendum and the spate of terrorist attacks in 2017.

The number of people referred to the UK government’s counter-extremism programme over concerns about far-right activity has also risen, according to the most recent official statistics.

In 2017-18, 7,318 individuals were referred to Prevent, of whom 1,312 – 18% – were referred for concerns related to rightwing extremism, up from 16% in the previous year.

For the first time, a similar percentage of individuals received support from the Channel scheme for concerns related to Islamist and rightwing extremism. Channel, which is part of the Prevent strategy, provides specialist support to people who are at risk of being drawn into terrorism.

Of the 394 individuals who received Channel support, 179 or 45% were referred for concerns related to Islamist extremism and 174 or 44% were referred for concerns related to rightwing extremism.

Since 2018, MI5 has taken on an enhanced role in the fight against far-right terror groups, which it had previously left to the police.

The most high-profile cases of far-right violence in recent years were the murder of the MP Jo Cox by the white supremacist Thomas Mair and the foiled plot to kill the MP Rosie Cooper by Jack Renshaw, a former member of the banned group National Action.

But there have been numerous cases in the courts in the past year with far-right links. The most serious examples include Vincent Fuller, who is to be sentenced for attempted murder next month after admitting to stabbing a Bulgarian teenager in a Tesco car park in Surrey in a racially aggravated attack.

Last month, Tristan Morgan, a far-right extremist from Devon, admitted attempting to burn down a synagogue, and two teenage neo-Nazis who encouraged terror attacks on targets including Prince Harry were jailed in June.

Mulhall concludes the shift in perceptions of the far right is less a matter of traditional signifiers, such as racism, becoming acceptable in British society, but more down to key far-right operators focusing on specific areas that resonate with prevailing public attitudes – such as mistrust of Muslims, a sense that rights such as free speech are being suppressed and pushing an “oppressed people versus a corrupt elite” narrative.