I might be late to the Oldham East and Saddleworth by-election commentary party, but there's something I'd like to add about the turn out (see Boffy for a wider analysis, and Andy on Ed Miliband's subsequent love bombing of the LibDems).
I've come across the odd Tory or two trying to rubbish the wide margin by which Labour held the seat. Their argument goes that a majority of 3,558 is hardly encouraging when turnout was down to 48% from the 61% of the general election (if this should be a sobering result for Labour what does a feeble 4,481 votes mean for them?). But the Tories do have a point, don't they? Should a 13% fall in turnout be cause for concern?
Not really. Political science distinguishes between first and second order elections. The first order are taken more seriously by the electorate at large and refer to general and presidential elections. i.e. Those determining the political colours of a national government. Second order is every sort of election below this level. Falling into this category in the UK are the Scottish parliament, Welsh, Northern Ireland, and London assembly elections, European elections, local elections, referendums and by-elections. In the eyes of the electorate these tend not to matter so much and therefore turnout is invariably depressed compared with general elections. To illustrate, turnout at the May 2010 general election was 65.1%. Elections for the devolved governments were 51.8% for Scotland and 43.7% for Wales in 2007 (Northern Ireland saw a turnout of 62.1% - reflecting the higher levels of politicisation in the province). The 2008 London Assembly election saw 45.3% and at 2009's European elections it was only 34%.
Therefore attaching any kind of significance to a by-election result depends in large measure on how its turnout compares with other second order elections. In Oldham East and Saddleworth's case its 48% holds up very well in comparison to recent mainland Britain elections. The same is true of the by-elections fought during the last Parliament. In reverse order the last five before May 2010 were Glasgow North East (33%), Norwich North (46%), Glenrothes (52%), Glasgow East (42%), Haltemprice and Howden (34.5%).
It stands to reason the strengthening of Labour's support in Oldham reflects the wider turn to the party reported in poll after poll - whatever grumbling Tories might think.