Owen Jones: Ukip offer a respectable outlet for those with racial prejudices

However abrasive they may be in public, political figures are often privately charming, and Ukip leader Nigel Farage is no exception. A few months ago, I took part in a BBC Schools Question Time with him; that a hard-right ideologue who left the Tories in disgust when they booted out Margaret Thatcher could win the affection of a crowd of state-school sixth formers underlined his potential. Unlike, say, the rather dour hang-and-flog-em journalist Peter Hitchens, Farage is jovial, playful and often witty. Political poison, too. Continuing a debate after the recording on why poorer children did worse at school than their more affluent peers, he suggested to me that genetics played a role: I winced.

It remains to be seen whether Ukip is solidifying its position as Britain's third party, but recent opinion polls and by-elections seem to point in that direction. As the Not-So-Strange Death of Liberal Britain continues apace, Ukip are filling the vacuum. In yesterday's ComRes poll for the Independent on Sunday, they registered 14 per cent – approaching half of the Conservatives' poll rating. On average, the candidates they fielded in May's local elections won the same level of support; over 5,000 Rotherham residents opted for their candidate in the recent byelection; and Farage is confident that Ukip will win the biggest share of the vote in the 2013 European Parliamentary elections. Their membership is apparently being bloated by Tories fleeing in disgust at the prospect of equal marriage. For now, at least, Ukip are on the march.

Despite frequent suggestions from the right that the BBC is some sort of pinko-lefty conspiracy, Ukip's rise has been aided by generous media exposure. On the Beeb's flagship political programme Question Time, for example, Nigel Farage has appeared more times since 2008 than any politician other than Vince Cable, and his deputy Paul Nuttall made two appearances this year alone. But what little scrutiny Ukip has received, even as they become a permanent fixture in British politics.

Today's Ukip supporter is rather different from just a few years ago. Those voting for Farage's band are no longer affluent, middle class ex-Tories – often in the Shires – who are primarily obsessed with fleeing the sinister clutches of the EU. As Matthew Goodwin, an expert on far-right extremism, has put it, it now "tends to do best among working-class voters who find its populist attacks on immigrants, Muslims and the political establishment attractive." Yesterday's poll bears that out: Ukip enjoyed the support of nearly a fifth of skilled workers, significantly more than middle-class professionals.

Neither can Ukip voters simply be dismissed as "the Thatcherite Tory Party in exile". Over four out of 10 Ukip voters oppose George Osborne's cap on tax credits and benefits, compared to just 15 per cent of Tories; and 43 per cent want an increase in spending on public services, a view shared by just over a quarter of Conservative voters. 40 per cent believe that the recovery is taking too long because the Government "is cutting spending too deeply" – more than remaining Liberal Democrat voters who subscribe to such a view. It all shows what a potentially fatally unstable coalition Ukip is: after all, Nigel Farage assails Osborne for not making enough cuts.

Indeed, Ukip's economic policies are a hard right wet dream – and a nightmare for the rest of us. They propose a flat tax of 31 per cent for all but the very poorest, leaving millionaires paying the same as call centre workers, nurses and bin collectors. They want to abolish employers' national insurance contributions, which the IFS estimate would be a tax cut for bosses of up to £60bn, leading to even more traumatic cuts. They are climate change deniers and want to scrap subsidies for renewable energy, favouring increased support for nuclear power stations instead.

But it is the fact that they threaten to tap into a huge potential well of bigotry that makes them such a threat. Other Western European countries have long been afflicted with thriving right-wing populist parties; Ukip looks like it has a shot at establishing themselves as Britain's equivalent of the French National Front. With their campaign against gay marriage, Ukip hope to win over obsessively homophobic Tories. Ukip MEP Roger Helmer once compared gay marriage to incest and polygamy, and Dr Julia Gasper – who stood for the party in Oxford East in 2010 – once mused: "We ought to reflect that there is a strong connection between male homosexuality and paedophilia." To top off all the offensive comparisons, Ukip's cultural spokesman Winston McKenzie suggested that putting children with lesbian or gay couples was "child abuse". In the European Parliament, Ukip sit with hardline homophobes such as the far-right United Poland party. Little wonder, then, that former Ukip MEP Nikki Sinclaire has put it, Ukip are "without a doubt homophobic".

Above all, Ukip offer a respectable outlet for those with racial prejudices. As professors Peter John and Helen Margetts have put it, Ukip "draws upon the same source of social and political attitudes among the public as the BNP and has the potential to convert such attitudes into votes". After protracted campaigns by anti-fascists, the BNP are in meltdown: but Ukip offer a home for those turned off by the fascist associations of Nick Griffin's thugs. With dog-whistle policies such as banning the burqa, Ukip are tapping into the poison of Islamophobia. "Multiculturalism has split our society," Ukip claims, promising the end the "active promotion of the doctrine of multiculturalism by local national government and all publicly funded bodies." Last week's census exposed the myth that we are becoming a more racially segregated society, with the number of mixed-race children doubling in just a decade. People from different backgrounds increasingly live together, work together and – yes – sleep together. But it is those fearful of Britain's growing diversity that Ukip is desperate to appeal to.

Ukip's rise represents a failure of the left. Even as capitalism remains in an intractable crisis, left-of-Labour parties in Britain are incapable of channelling people's growing frustrations, winning derisory votes in each election. Ukip has become a vehicle for those repulsed by our technocratic political elite. But be in no doubt. Charming Farage is a politically dangerous man, and Ukip are a real potential menace. It's time to take them seriously.