It’s easy to forget that our votes are for individual MPs
One of the main phenomenons seen at general election after general election is how tough it can be to unseat a sitting LD MP.
Invariably, Lembit excepted, the experience is that sitting MPs tend to perform better than the national average. Maybe this chart, based on an article by Prof Phil Cowley, is part of the explanation.
This is from Professor Cowley’ article in Total Politics:
Lib Dem MPs appear to be able to reach across that divide. Even among non-Lib Dem voters, Lib Dem MPs scored +7. Amongst Lib Dem-voting respondents who had a Lib Dem MP, the score was an astonishing +61
How this will play at GE2015 we don’t know but the more that the LDs can focus on the local in their constituencies the more seats they will retain.