IMHO there's not really too much to read into Labour's triple by-election victory yesterday, except that Middlesbrough must be full of Labour drone-clones because they nearly managed the impossible of getting the same number of votes as in a general election. [09:06 a.m. scratch that, misread]. I have adapted a graph (left) taken from a good amount of information on the Rotherham constituency at 'all that's left'here and added yesterday's results. Good analysis from Durotrigan ("good for UKIP, better for Labour") and a handy table of the numbers from Raedwald ("LibDems utterly destroyed in by-elections").
Update: Apparently 50% of the votes were postal votes...(Here, scroll down to 11:51 am).