Mike Smithson has a good post on Political Betting this morning where he highlights the final 12 polls of the election campaign (you know, the ones that all massively overstated the final support for the Lib Dems).
In the post, Mike suggests that the Lib Dem vote may have "melted away" as large numbers of people changed their mind on the day itself. This would suggest that the polls may not have actually been wrong. Many of them did pick up on this volalitity in the underlying data and I recall being worried about it myself as to how soft the Lib Dem vote was.
The post also quotes former pollster Robert Walter:
“..Essentially the view is that the campaign polls were not wrong, but when confronted with an actual choice of government on the day, voters turned away from the ‘lighter’ alternative stimulated by Clegg and the debates, to make a very serious decision between the two main contending parties about who to trust to govern for the ensuing years.This view, which is not unknown on academic circles, has always struck me as valid. Voting is not a consumer choice between packets of cornflakes, more like choosing professionals to represent over a long period of time."
This also rings true. Both Labour and the Tories repeatedly made the point "The Lib Dems can't win" during the election campaign and the fact that the party had not held power for 65 years played to the age old narrative that a vote for the Lib Dems is wasted.
The fascinating thing about the next election however will be whether this sort of effect will work any more. I suspect not. The fact that the Lib Dems will have been in power will I expect have all sorts of other effects, some good, some bad. For example there will be a record to defend, a detailed job of communicating to people which parts of the programme were from our manifesto, making sure we are seen as distinct from the Tories, rebutting the claim that we propped them up etc. etc. etc. But one thing that will no longer be credible is the idea that there is no point in voting for the Lib Dems at a national level. That will clearly be untrue.
So although there may be all kinds of other consequences from the coalition for the pollsters to cope with, I suspect that this particular one may actually resolve itself.