The Lib Dems have just launched a rather clever campaign for the "Labservatives" which urges voters to break the two party domination of British politics.
Now I have a lot of sympathy with this. I think voters should be encouraged to vote for whichever party they want to win, regardless of their electoral chances.
So why is it that the Lib Dems are so keen on dodgy graphs like this?
Or indeed this?