I have spent a long time looking at the 2010 Lib Dems because this group is going to play a central part in the next election. I am now going to summarise my conclusions, to put them all in one place.
1. The Lib Dems' decline has been so steep, uniform national swing is no longer a reliable tool. This is particularly apparent in Scotland (where the maths wouldn't work in more than half of all Scottish seats), but it is true in the rest of the UK also.
2. Such polling evidence as we have suggests that in seats that the Lib Dems will not be seriously contesting, they are doing better than uniform national swing would suggest. This is unsurprising, since there will always be a residual level of support and these seats had fewer Lib Dem voters in the first place. The proportion staying behind seems to be in proportion to the national opinion polls - though it should be stressed that we have very limited and not hugely reliable data.
3. The corollary of this is that at present the Lib Dems are doing worse in the seats they are seriously contesting than uniform national swing would suggest.
4. In the seats that the Lib Dems are not seriously contesting, their 2010 voters who have deserted them have so far decisively broken for Labour. I have made some assumptions about the proportion of voters in each seat that has shifted to Labour, which gives a very different impression of the order of marginality of seats.
5. As a consequence, Labour have secured a substantial strategic shift in the marginals. It will be much easier for them to secure most seats or an overall majority than the results alone suggest (though the effect seems a bit more muted than some have suggested owing to the relative outperformance by the Lib Dems in these seats). This accentuates the already substantial advantages that Labour has I the electoral system.
6. The Lib Dems,on the other hand, can take no particular comfort from their past outperformance of uniform national swing. The scale of the drop in support will make this much tougher this time around.
That's the position now. What might change these voters' minds over the next year?
I suggest the answer is different in different types of constituency. Those 2010 Lib Dems who have taken a leftward turn are normally going to stick with their current choice. They've decided what they think of the current government and it's not positive (to put it mildly). In Labour/Conservative marginals, that means Labour. In Labour/Lib Dem marginals, that means Labour.
There are two interesting cases. In Scotland, disaffected left-leaning Lib Dems have the additional option of the SNP. Many of them will take it. Some of these voters will rule out the other left of centre option, while many will be open to both choices. In seats where both Labour and the SNP are viable options, there remains the possibility of swing between these parties.
This could aid the Lib Dems in constituencies where there is confusion about who is the best-placed left of centre challenger. In constituencies where it is clear who out of Labour and the SNP is best placed to win, these votes will mostly end up with that challenger.
Similar thought processes are presumably also at play in Wales with Plaid Cymru and in those few English seats where the Greens are credible challengers.
What of those seats where there is no other left of centre challenger capable of winning? The Lib Dems have traded heavily on tactical votes from the left in the past. But can they repeat the feat after making five years of the perceived betrayals and compromises of coalition government with the Conservatives?
Rationality would suggest yes. This is the sensible, if unappetising choice, for voters who see the Lib Dems as better than the Conservatives, even if the difference is not as great as they previously understood.
But voters are not entirely or even mainly rational. Some will make the rational choice while some will want to register their unhappiness by voting with their heart or by simply not voting at all. The unanswered question is how angry these voters remain.
It is reasonable for the Lib Dems to hope to woo these voters back. In the next year, they need to find the positioning and message to reach those of these voters who are unreasonable. They have it all still to do.