So *was* there a "late swing" to the Conservatives from other parties in #GE2015? as some voters considered between a Conservative government and a Labour Government supported by the SNP?

Here's our evidence FOR a late swing using our data:



And as stated on the graphic, we've prepared the raw data files for independent review.

The SPSS file is ready- email us and we'll share with any interested persons.
 

Based on this evidence we conclude that the polls were correct at the time they were conducted, including  our May 6th telephone poll which we considered at the time an ‘outlier” given the amount of apparent counter information and did not release. See this article for info:  http://survation.com/snatching-defeat-from-the-jaws-of-victory/ 

There was a late swing to CON, most likely based on the “this is a CON vs a LAB/SNP joint ticket” messaging from Nick Clegg & David Cameron. See below personal letter sent from David Cameron in marginal seats - this example from a voter in the South West:

 

Finally, around 5% of Conservative 2015 voters in our post-election questionnaire (May 8th) explicitly mentioned fear of the SNP as their number one reason for voting Conservative, whilst many more gave responses along the lines of “to ensure stability”, “protect the UK” or similar which could well have been alluding to the fear of a Labour-SNP deal.