Between the 2007 and 2011 elections some significant changes were made to the constituency boundaries (the map is here – large pdf – as per the pic to the left). This makes it hard to show changes in votes cast or in the share of the vote. However, with caveats, we are very grateful to Professor David Denver, who calculated best estimates of what the 2007 results would have been if the new constituencies had been in place then. His paper is available here.
The 2011 election results pages here on Better Nation therefore compare the real 2011 results with Denver’s notional 2007 numbers to give a better idea of the real change in voting patterns. And if you’re in the pub and someone talks about the vote swing in a specific constituency (unlikely, of course) you can be the biggest election dork there by asking if they mean change relative to the Denver Notionals.