The post attracted a lot of traffic and several comments not least from one Ben Goldacre, journalist, doctor and author of the Bad Science blog. I used ICM/Guardian data and plotted a graph showing the decline in votes over the last 20 years for the two major parties. He accused me of bullshitting and repeatedly called me a twat because I had omitted data from 1984-1990 that was available from the Guardian. In fact the reason for starting from 1990 was because 20 years seemed like a good length of time to support the argument and there was a blip in the early eighties caused by the split of the SDP from Labour and their alliance with the Liberals. I ought to point out that I wasn’t entirely blameless in the exchange in that I suggested he’d had a drink or two. Sorry Ben.
I am now posting using election data from the last 50 years and the latest poll data for 2010. I think the picture is pretty clear and undistorted and supports the earlier hypothesis. The combined support for the two main parties has been falling for 50 years. If that continues and there is no proof that it will then two-party politics is on the way out. The defining moment might just be on Thursday.