Labour is divided about how seriously it should take Ukip.
Those in Ed Miliband's team who cling to the misguided view that Nigel Farage's party is not a threat should look at the Labour seats that are most vulnerable to this insurgency. I have identified Ukip's top prospects in Labour territory by drawing on the latest data from the census and Ukip's results in 2014 and 2010. The analysis also takes into account how much wider potential support there is for Ukip in a seat - the 'Ukip Plus vote'- which is based on how many people either voted for smaller Eurosceptic parties in May (e.g. An Independence from Europe, NOTOEU and We Want a Referendum Now) or the far right. Ukip will likely win over these voters at next year's general election, and at least 50 per cent of BNP voters.
The Labour seats that emerge as top prospects for Ukip share several features; they are typically over 95 per cent white British; have large numbers of pensioners and voters with only GCSE or no qualifications; and in 2014 saw Ukip win the popular vote. But it is the local political context that will be crucial at next year's first-past-the-post election. While many Labour seats have ideal conditions for Ukip, they have healthy majorities that will be impossible to overturn in 2015. Stoke-on-Trent is a good example; in May, the 'Ukip Plus' vote reached almost 50 per cent, but popular Labour MPs like Joan Walley are well entrenched, and have experience of fighting off the BNP. Ukip need seats that not only have lots of receptive voters but also favourable political conditions where the vote is split across the main parties, making a third party insurgency possible. Keeping this in mind, here are the five seats where Ukip is likely to damage Labour at the general election.
Number 5: Rotherham That Ukip is excited about its prospects in Yorkshire is reflected in its decision to stage its annual conference in Doncaster in September. Many of its activists have are eyes on the nearby seat of Rotherham where Ukip has history; it polled 22 per cent at a by-election in 2012, took 41 per cent at the recent European elections (beating Labour by 7 points), and also polled over 40 per cent at the local elections, winning ten wards and finishing closely behind Labour in the remaining eleven. Rotherham has been Labour since 1933 and so a Ukip win is unlikely. But it is on the list because of what it represents; a struggling northern working-class seat where Ukip is already established as the second force. Rotherham may well slip onto Farage's list of top targets as he thinks about ways to exploit the possibility of an unpopular post-2015 Labour government.
Number 4: Dudley North At first glance this seat might seem an odd choice. It has an usually high percentage of ethnic minority voters for Ukip (12 per cent) and last year a Survation poll put Ukip in a distant third, on 23 per cent. But such weaknesses are offset by Ukip's strong local branch, led by its MEP Bill Etheridge, He has worked the seat hard, fighting all but one local seat in 2012 and was rewarded at this year's European elections when Ukip took 38 per cent, 12 points clear of Labour. There is wider potential for Ukip; in 2005 and 2010 almost 15 per cent of the vote went to Ukip or the far right. Ukip's effective local machine could hoover up this vote and pose a serious challenge. Assuming this happens, Ukip only need a two-party swing of around 13 per cent to take the seat.
Number 3: Ashfield After taking just 1.9 per cent in this former mining community in 2010, Ukip bounced back this year to finish 8 points clear of Labour on 37 per cent. Gloria De Piero's majority is just 0.4 per cent while the vote is split across the main parties. Ukip is also helped by a tradition of anti-Labour voting in the seat, which has disrupted old loyalties. Independents have been strong here. In 2010 the Ukip Plus vote was already 11 per cent and at the recent European elections combined support for radical Eurosceptics reached 44 per cent. Can Ukip consolidate these votes?
Number 2: Plymouth Moor View The seat is in the more working-class part of Plymouth and like other southern coastal areas where Ukip polls well it has a high share of pensioners. Ukip's 7.7 per cent in 2010 disappointed its activists who had invested heavily but this year the party topped the poll with 37 per cent, 14 points clear of Labour. Again, the vote is split quite evenly across the main parties while the southwest is one of Ukip's activist strongholds. If they want to devote manpower to this seat, they can.
Number 1: Great Grimsby This is by far Ukip's strongest prospect. We first identified the seat in our book, Revolt on the Right, because of its ideal demographics; old, white, working-class and low levels of education. Ukip have since gone from strength to strength; they won the popular vote in May with 41 per cent, some 18 points clear of Labour (the Ukip-Plus vote is 46 per cent). Ukip has also built ties with local voters by fighting lots of local seats between 2010 and 2012, while Austin Mitchell who has held the seat since 1977 is standing down, removing the local incumbency factor. Ukip are likely to officially select the competent Victoria Ayling, who has intimate knowledge of the seat having won 30 per cent of the vote as a Conservative candidate in 2010. Will Labour's new PPC -35 year-old Melanie Onnbe able to defend a majority of only 2.2 per cent and hold Ukip back?
These are Ukip's best prospects in 2015, although they are not the only Labour seats that are vulnerable to Ukip's insurgency. The same cocktail of economic stagnation and rising Ukip support can be seen in seats like Bishop Auckland, Blackpool South, Don Valley, Mansfield, Scunthorpe, Stockton North, Walsall North and Workington, though Labour incumbents are often better entrenched. Should Labour return to power next year there is a wider ring of seats that Ukip will no doubt target in new sets of local elections and where it is already polling strongly; Bootle, Bolsover, Blackpool North, Doncaster, Hartlepool, Knowsley, Middlesbrough, South Shields, Stoke-on-Trent and parts of Wales like Blaenau Gwent, Rhondda, Swansea East and Torfaen look safe for now, but falling Labour majorities are meeting a resurgent Ukip.
Labour's problem is that it continues to view Ukip through a narrow lens that is only concerned with what this insurgency means for the national outcome in 2015. But as these seats show, locally Ukip is quickly embedding itself in a diverse range of areas and is thinking far beyond next year. In the 1980s, social democrats used to think along the same lines about the radical right Front National; they even encouraged its rise because they believed it “divided the right”. Look at how that turned out.
Dr Matthew Goodwin is associate professor of politics and international relations at the University of Nottingham