In late January, a column of demonstrators marched in driving sleet through the West Yorkshire town of Dewsbury, chanting: “Britain First, fighting back.”

Although the group has amassed more than 1.4m Facebook likes, greater than any other UK political party, the number of actual boots on the ground for Britain First, a relative newcomer on the far-right scene, was not that impressive. Just 120 supporters assembled to march from the train station to the town hall, escorted by many police and jeered by many residents.

Yesterday Thomas Mair from the West Yorkshire town of Batley, a mile north of Dewsbury, appeared at Westminster magistrates court and was charged with the murder of MP Jo Cox.

There has been considerable speculation that the 52-year-old may have had links to far-right groups. Whatever the truth, there is no doubt that an extreme right-wing element has established a disturbing foothold in the post-industrial social landscape of West Yorkshire.

According to experts, at least seven far-right groups united by racist ideologies are active in the region, an area dominated by Leeds and Bradford. Activists pinpoint a hardcore cohort of 100 prominent individuals able to cite the broader backing of thousands of social-media supporters.

Among the far-right organisations in West Yorkshire are the virulently anti-Muslim English Defence League (EDL), which claims to have established “divisions” in Leeds, Huddersfield, Halifax and Dewsbury, along with the British Movement (BM), a small but ultra-violent group considered extreme even by the standards of the British far right.

Other organisations include National Action, a neo-Nazi nationalist youth movement that openly advocates violence and whose strategy document reportedly makes reference to Hitler.

The neo-Nazi National Front, which advocates repatriation for non-whites, has a presence. Anti-racism activists also point to the Britain Democratic Party, a modest organisation founded by a group of former BNP politicians including Andrew Brons, former MEP for Yorkshire and the Humber, who has hosted seminars on racial nationalism. The Yorkshire Infidels belong to a regional network of far-right nationalists whose marches have descended into violence.

There have been at least seven marches by the far right in West Yorkshire during the past two years, including the Dewsbury turnout in January. In May 2015 the EDL marched in Halifax; two months later the National Front demonstrated in Wakefield; and in November the EDL marched again, this time in Bradford in an attempt to provoke the city’s sizeable Muslim community. The Britain First demonstration cost £445,000 to police.

According to Prevent, the government’s counter-extremism programme, the region’s small but determined far-right nexus has led to far-right extremists accounting for half of all referrals in Yorkshire to its counter-radicalisation programme. Matthew Collins of anti-fascist group Hope Not Hate said: “West Yorkshire has always been active. When it comes to getting numbers, the north-west and the north-east are the hotspots, but Yorkshire always manages to get the numbers out.

The fluidity of membership among the network of Britain’s far-right groups is one recent trend tracked by anti-racist campaigners, who describe seeing the same individual attending a demonstration by the pro-Israel EDL and shortly afterwards marching with the antisemitic National Front.

“Everybody goes anywhere, it doesn’t really matter if one day they’re on an EDL march, the next on a neo-Nazi march. It’s not just the left living in post-ideological times, it’s also the far right.” The ideology to which Collins refers is the movement’s once-dominant doctrine of confrontational race war in which the state is considered a legitimate target, a stance articulated by Combat 18, a violent neo-Nazi group that emerged in 1992 and whose support has dwindled.

“Instead of having an overwhelming belief in the supremacy of the white race, they are more drawn to conspiracy theorists,” said Collins. “The far right in this country has shifted from out and out white supremacism towards anti-liberal ideas – it has shifted towards the Daily Express, Daily Mail editorials, as opposed to the traditional neo-Nazism,” said Collins.

Why West Yorkshire? Some speculate that the region’s high Muslim population has amplified far-right sentiment, giving Islamophobic groups a visible “enemy” to rally against. In Bradford, for instance, nearly one quarter of the population is Muslim and, overall, Yorkshire and the Humber has a Muslim population of 6.2%, compared with the UK average of 4.5%. But those statistics cannot provide the whole explanation.

“It’s got heavy pockets of Muslim communities, although so does the West Midlands, as does London, so that doesn’t really add up. The fact endures that there are many far-right groups active in West Yorkshire,” said Collins.

The region has long been viewed by mainstream right-wing parties as a natural stronghold. The BNP’s Nick Griffin dubbed the region its “jewel in the crown” more than a decade ago, at a time when it had enough support to contest every seat in some districts, including Leeds. In 2008 the party had 34 candidates in Leeds – one in each of the city’s 33 wards, and one in a byelection, but now the party’s support has dwindled to the point that it is considered irrelevant by many of its former backers.

Groups like Britain First, which critics have described as a fascist paramilitary group, are attempting to fill the gap. Its organisers are said to have planned an “unprecedented” number of events in the region during 2016. Its tactics are, to say the least, unsophisticated. Leader Paul Golding threatened last year to bury a pig at the site of a proposed mosque in the West Midlands.

According to campaigners, it is the existence of Redwatch, whose organisers are based in West Yorkshire, that encapsulates far-right hostility towards the left and liberalism. The website Redwatch publishes photographs and personal information relating to alleged far-left and anti-fascist activists, typically targeting officials, advocacy groups, trade unions and hostile media.

“They continue to publish the details of people, MPs, councillors, trade union activists and it still hasn’t been dealt with,” said Collins.

One aspect of the far right that has disappeared is West Yorkshire’s network of “book clubs”, where activists disseminated supremacist literature or imported race-war material from the US. One popular title, still available to buy online, is March Upcountry by Harold Covington, described on a message board of the supremacist organisation Stormfront as being about increasing “the effectiveness and influence of the worldwide White, Aryan resistance movement”.

The far right in West Yorkshire also has links to the US with the National Alliance, a once-prominent white-supremacist group based in West Virginia, whose British representative, according to Hope Not Hate, lives near Leeds.

Many believe that the threat from the far right has been consistently underestimated compared with Islamism, and in particular its capacity for “lone wolf” attacks. In 2013 Charles Farr, then director-general of the UK Office for Security and Counter Terrorism, warned that the threat from extreme-right-wing lone wolves was increasing. Many of the largest caches of arms found in the previous five years had been connected to the far right.

A recent study by the Royal United Services Institute accused western governments of neglecting the threat of far-right lone actor terrorists, with almost a third in Europe since 2000 having been motivated by extreme-right-wing beliefs, compared with 38% inspired by religion.