Scottish nationalism is still somewhat popular, but a lot of people voting for the SNP last time weren't actually voting for Scottish nationalism, but for a left party, an area in which Ed Milliband's labour was deemed to be lacking.

The shift to the Tories can explained by: 1. The popularity of Ruth Davies, leader of the scotrish conservatives. 2. The left vote being split between the SNP and Labour, allowing the conservatives to win under FPTP.