LIKE many in Heywood and Middleton, two former mill towns outside Manchester, John Bickley is fed up with the Labour Party. It was formed to take on the upper classes but has now joined them, complains this son of a Labour trade unionist as he denounces “Labour’s evil bankers” at Goldman Sachs. Despite appearances, however, he is no socialist. He is the local parliamentary candidate for the UK Independence Party (UKIP), a self-described libertarian outfit on the right of British politics.

For years UKIP’s calls for lower immigration, less regulation and withdrawal from the meddlesome European Union have challenged the governing Conservatives. The party gained 3% of votes in the 2010 general election, but the latest YouGov poll puts it at 15% (with the support of one in five former Conservative voters). Two right-wing Tory MPs, Douglas Carswell and Mark Reckless, defected to the party in the past few weeks. At the Conservative Party conference, which took place in Birmingham between September 28th and October 1st, journalists pursued other outspoken MPs through bars and meeting rooms, demanding to know whether they would follow.

UKIP hurts the Tories more than it does the opposition Labour Party, but it has started to give them the jitters, too. In local elections in May it stormed ahead in the party’s traditional strongholds—like Rotherham in Yorkshire, where it won ten of the available 21 council seats—and in bellwethers like Thurrock, an Essex constituency that Labour badly needs to win from the Tories at next May’s general election. Although UKIP is not expected to win the by-election due to take place in Heywood and Middleton on October 9th, Labour insiders fret that it will give their candidate, Liz McInnes, a run for her money.

How is a defiantly Thatcherite party (whose quotable leader, Nigel Farage, is a pinstriped former commodities trader) now threatening Labour? Asked that question during their visit to a health centre in Middleton, Ms McInnes and Andy Burnham, the shadow health secretary, mumbled something about protest votes. Their reticence was not surprising: the answers tend to show Labour in a bad light.

The first is that the party has become moribund in many of its working-class strongholds. Constituency Labour parties in London are thriving and comprise roughly half of the party’s membership. For example in 2010 (the most recent point for which a breakdown is available) the branch in metropolitan Holborn and St Pancras had 1,181 members. But elsewhere they are listless: the equivalent figure for Heywood and Middleton was 293. Half that number turned out for a recent weekend canvassing session. In contrast, even on a quiet weekday UKIP campaigners swarmed about Heywood. On buying a mug of tea your correspondent found himself being canvassed by a café-owner—a lifelong Labour voter who recently switched to UKIP. “Borders,” she shot back when asked her reason.

This points to another factor: Labour’s underbelly is softest in precisely those places where voters are receptive to UKIP’s isolationist messages. Robert Ford and Matthew Goodwin, academics who have studied UKIP’s rise, argue that it thrives among blue collars, grey hair and white skin; that is, in ageing working-class backwaters like Heywood and Middleton where folk feel alienated from the liberal values of the big cities. This requires Labour to contort itself, attempting to reconcile the values of its urban base with those of its small-town, conservative one—usually by talking about things like the National Health Service (NHS) which unite the two. If shadow ministers sound pained when asked about immigration, it is because they are experiencing the political equivalent of groin strain.

Supple not subtle

UKIP, by contrast, is a suppler gymnast. Its charismatic rejection of the po-faced establishment, embodied by its boozy, cheerful leader, is built on emotion, not policy. That gives it flexibility: it can make a small-state, libertarian pitch to Tory voters and wealthy donors while lambasting private-sector involvement in the NHS in Labour areas like Heywood.

As a result, both main parties find it hard to win back their defectors. Michael Dugher, Labour’s vice chair, points left-wing types to UKIP’s past support for a Thatcherite flat tax. Mr Bickley dismisses that claim, avowing that he would prefer a more progressive tax system. Tories warn wavering supporters that a vote for UKIP could let Labour in. Polls suggest most UKIP supporters do not really care; they see the main parties as an amorphous blob anyway. At the general election, then, the party will take votes from both Labour and the Conservatives, not just the latter. Peter Kellner, the president of YouGov, reckons that it could win as many as ten seats.

But as it does so UKIP’s contortions will become more painful. Its policies will come under new scrutiny, the sheen of insurgency will wear off and it will be held to higher standards of consistency. Already there are signs that its libertarian wing (dominated by its youth, its donors and Mr Farage) is peeling away from its conservative one (most of its supporters). At its buzzing conference in Doncaster on September 26th a spokesman announced the party would increase taxes on luxury shoes, handbags and cars. Two days later another declared the policy “dead”. Such strains are a sign of things to come as success causes even more problems. Eventually the bendy Mr Farage will pull a muscle.