One subject that is sure to remain the subject of controversy for the next few years is the extent to which Lib Dem voters can be harvested by the Labour party in opposition to the coalition. It is critical to the Labour party's strategy for the next few years. There is certainly a good deal of anecdotal evidence that many leftwing Lib Dems are profoundly uneasy about the coalition and Lib Dem polling is down, while Labour polling is up (though most pollsters have seen a rise in Conservative polling also). How might this translate into a strategy in marginal seats on the ground?
Where (politically) are the Lib Dem voters?
The first (slightly surprising) thing to note is that Lib Dem voters are to be found in substantial numbers almost everywhere. I attach a table (Asterisks against the name of the constituency indicate that Labour is third. Obelisks against the vote share indicate that the Lib Dem vote share was static or fell.):
On the list of Labour's top 150 targets, 125 of those seats are Conservative-held. The Lib Dems polled more than 10% in each and every one of those seats. It increased its vote share in 92 of these seats. This is not the performance of a party being relentlessly squeezed in a marginal.
By way of contrast, Labour polled under 10% in 12 out of the first 13 Lib Dem-held Conservative targets. Indeed, in the 20 English Lib Dem seats in the top 100 Conservative targets, Labour polled under 10% in all bar three: Norwich South and Bradford East (in both of which Labour finished second) and Berwick-upon-Tweed. In several cases, Labour lost its deposit. In every one of these 20 seats, Labour's vote share was down and usually substantially. Labour's vote share was also down in all of the first 20 Conservative-held Lib Dem targets. While it polled above 10% in 9 of these, this is less good than it looks: it had held four of these seats before the last election and been second in two more).
It has to be said that it is the Labour party's amazingly low vote shares in Conservative/Lib Dem marginals that is exceptional, not the Lib Dems' higher vote shares. The Conservatives have not been squeezed anything like as hard in Labour/Lib Dem marginals. In only one of these seats on either the Labour or Lib Dem target list is the Tory tally below 10%: Dunfermline and West Fife.
The logical conclusion, therefore, is that historically Labour voters have been unusually willing to vote tactically in Lib Dem/Conservative marginals (and this is borne out by anecdotal experience). If this is so and these are many of the voters who are thinking about no longer voting tactically, the main beneficiaries will be the Conservatives.
Where (geographically) are the Lib Dem voters?
I attach a list of the Conservative-held Labour target seats broken down into categories of Lib Dem vote share:
Many of the Labour/Conservative marginal constituencies where the Lib Dems have polled particularly well fall in two areas of relative Lib Dem strength. In an arc stretching from Warrington South in the south west, through Altrincham & Sale West, through three Lib Dem-held constituencies, Wythenshawe and Sale West, Stockport, through High Peak, Colne Valley, Calder Valley, Lib Dem-held Burnley and Pendle, the Lib Dems have an arc of seats curving around Manchester in which they scored at least 20% and more usually 25% or more.
There is of course an even hotter spot in the south west. 49 out of 55 seats have at least a 20% Lib Dem vote share and more often 25% or higher. More than 30% is the norm. The Lib Dems hold 15 of these seats.
Set against this, there are areas of relative Lib Dem weakness. There is something in the Thames estuary water, because there isn't a single seat abutting the water from Bethnal Green & Bow to Castle Point on the north side inclusive and from Erith & Thamesmead to Gravesham on the south side inclusive where the Lib Dems tally more than 15%. Perhaps the Lib Dems don't do unglamorous very well.
All of which is leading into the fundamental question...
Who votes Lib Dem anyway?
Many Labour supporters are very fond of the notion that Lib Dems are pseud0-Labour supporters: people too well brought up to vote Labour. Certainly, the Lib Dems have been very happy to take advantage of this notion in Conservative-held seats where Labour cannot win. But in seats that the Lib Dems could not win and were not even second, the Lib Dem vote share and absolute numbers of votes generally went up at the last election. If these voters were fundamentally left-leaning rather than right-leaning, why didn't the Labour party's message not to let the Tories in work this time in Labour/Conservative marginals? Come to that, if these voters hated Gordon Brown so much, why didn't they vote Tory? The answers to these questions should determine Labour's strategy to win the next election.
I don't have definitive answers, but here are a few suggestions as to why voters might vote Lib Dem in a Labour/Conservative marginal:
Not voting tactically, but for the preferred party
This, I suggest, will make up a plurality of Lib Dem voters in such seats. Lots of voters don't vote tactically, some because they haven't considered it and some because they won't consider it. That then leads onto the question of what the Lib Dems offered that neither Labour nor the Conservatives offered. I suggest that the answer is a reliability on civil liberties, a wish to redistribute but not to soak the rich, a genuine interest in localism and an open inclusive tone on immigration and the EU, coupled with the most pacific internationalist tone. They offered economic soundness via Vince Cable and an exciting, charming fresh faced leader in Nick Clegg.
There is a definite regional range in Lib Dem support. In the southwest, the Lib Dems have largely supplanted Labour as the opposition to the Conservatives. Around Manchester, the Lib Dems have made major advances in former Conservative territory. Labour should not assume that a single message will work equally well with all who supported the Lib Dems positively at the last election.
The range of positive Lib Dem voters will respond differently to the coalition depending on their competing concerns. Some assets have been downgraded: Nick Clegg is in the shadow of David Cameron, Vince Cable has been sidelined, the cuts have bitten more strongly than most Lib Dem voters probably would have liked. Set against that, the budget did include a raising of tax threshholds in line with Lib Dem wishes and the civil liberties and localism agendas have been honoured. The coalition has been winning the argument with the public about the need for cuts, even if they are disliked in concrete terms.
I suggest - I put in no stronger than that - that if the Lib Dems do lose ideological votes in these seats, then it is not immediately obvious that those ideological votes will go to the Labour party rather than the Conservatives.
Single issue voters
Some voters vote for a party on the strength of a single issue. Labour probably should not chase these voters.
There are plenty of voters out there who wanted to register their alienation at this election. The big two parties polled a lower combined vote share than has been seen in any of our lifetimes (excepting JackW). The Lib Dems were partial beneficiaries of this, though other parties benefited also.
If these voters still feel alienated at the next election, they will not vote for any of the main three parties. The Lib Dem vote share will go down, but Labour would not benefit. Labour needs to think about how it can get these voters to identify with it.
Closely allied to protest voters are those voters who wanted to stick two fingers up at the establishment. They genuinely did not mind which of Labour and the Conservatives got in.
These voters are possibly easier for Labour to win. They are not exclusive to the Lib Dems: the Greens, BNP and UKIP all got such votes (UKIP actively encouraged them). If after five years the establishment is Lib Dem and Conservative, Labour may benefit here.
Voting for the candidate
Some voters vote for an individual candidate. It seems doubtful that too many third placed Lib Dems benefited from this, but you never know. Anyway, Labour will have to address this through candidate selection.
The summation of all this is that Labour probably do have a bit of an advantage in winning over anti-establishment voters and have plenty to work with in winning over positive Lib Dem voters, but that they don't have all that great an advantage over the Conservatives when squeezing the Lib Dems, even if the Lib Dem vote flakes away. They should be planning carefully on a message that appeals to soft Conservative voters also.