Election campaign
The biggest swings at the election may well be in Scotland
I wrote yesterday of how Labour will need a 19.7% swing to defeat Nick Clegg at the election, while the SNP will need a 20.8% swing to unseat Douglas Alexander.
The size of these swings relative to those typically seen at general elections is enormous – but they are not uncommon.
At the last election, three constituencies saw swings of over 15%. One even topped the 20% mark:
The result in Redcar was a gain for the Liberal Democrats from Labour. It was a remarkable turnaround in a constituency that once boasted former Northern Ireland secretary Mo Mowlam as its MP. Ian Swales was the victor in 2010, but he is standing down this year and I fully expect Labour to retake the seat.
None of the other seats in this top five changed hands at the 2010 election. Ashfield, Merthyr Tydfil & Rhymney and Barnsley East remained Labour seats, despite the Lib Dems coming within 192 votes of taking Ashfield. All three ought to be held by Labour this year.
The Tories had won Hemel Hempstead from Labour in 2005, and at the 2010 election Mike Penning turned his majority of 499 into 13,406. He’ll be safe this year.
It’ll be fascinating to see if we get any swings on 7 May that beat Redcar. I wouldn’t be at all surprised if the record was set in Scotland.
UK elections 2015 
The biggest swing will surely be in Clacton (if you measure the swing between GEs), but that’s obviously an exceptional case. UKIP didn’t even contest Clacton in 2010 because they knew Carswell was quite UKIPpy and didn’t want to risk a spoiler effect.
Aside from that, the biggest swing will probably happen in Scotland, though I’ve no idea where. Motherwell and Wishaw showed the biggest swing of any of the seats in the Ashcroft poll so that’s a good starter. I expect it will come in an allegedly “ultra-safe” Labour constituency as those seats have the most votes to lose.
I quite like Kirkcaldy & Cowdenbeath for this. Party Leaders – and PMs even more so – get a recognition boost, and Gordon Brown had built up a personal vote over many years too.