I would doubt that many labour votes tactically switched. I would suspect that a good few labour voters who voted UKIP feel they made the right decision after that tweet
It looks like one of the easier votes to explain on simple extrapolation
In 2010 the total votes cast was 47,431. In 2014 it was 40,065, a decline of 7,416
In 2010 the Liberals polled 7800 and yesterday they polled 349. Their vote fell by a remarkably similar number, 7451. Just 35 in it. The liberal vote simply stayed at home. Mixed news for the Cameron party. Clearly the spirit of coalition doesn't extend to Rochester and Strood, but then Labout isn't picking the disaffected liberal either. They're abstaining.
UKIP however have found 16,867 votes from somewhere.
Well if we say that they aren't liberal, and the lower turnout would lead us into believing they aren't new voters, logic says they've come from the other two parties.
Conservative vote fell by 9,657 (or 14%)
Labours vote fell by 6,938 (or 11%)
add them together and we get 16,595 which is pretty damn close to UKIP's polling figure of 16,867 (272 difference) albeit we've got English Democrats clouding the issue slightly from 2010
Now we're guessing
If these are Labour voters turning to UKIP then Miliband has a problem. But this was never a Labour seat even if they held it once on the old boundaries and might have entertained some narrow hope in a classic squeeze. If these were Labour voters turning to UKIP tactically though, then Cameron's got the problem.
Cameron is going to lose more votes to his sister party than Labour (as he did here). There is still too much that's incompatiable with UKIP for Labour voters to make that transfer philosophically. They might pick up the working class immigation vote, but that's about the only common ground they'll appeal to. The Tories have a bigger rump of nationalist voters anyway, not to mention that they'll be more plugged into a lot of UKIP's other policies. As these get examined under a proper campaign the more Labour voters will withdraw from UKIP. Will the Tories though? Less so I'd have said
Something tells me we haven't heard the last of the tactical vote, becuase this is the critical issue, the Tories will certainly have no qualms about using it themselves. The pyscology of the tactical vote is different. The Tories will be more disposed towards voting for UKIP to unseat Labour MP's (possibly something we recently saw with a near miss in Chorley) but Labour voters will be more preapred to do it if they can convince themselves that its a duty to beat the Tories. They'll only do it though if they can see that the Tories are beatable in southern England to this tactic, and that requires Tories (as they have at Clacton and Rochester) to put some fuel into the UKIP boliers
Those who end up on the high mile ground might be the liberals yet when they throw George Osbornes AV literarture back at him which pointed out that FPTP wouldn't let this sort of thing happen. We could easily end up with AV yet