Here's something to really bake your noodle - if you simply reverse the Labour and Tory standing in the polls (leaving Lib Dem and Other as they stand), you get a hung parliament:
http://news3.thdo.bbc.co.uk/nol/shar...CULATE+RESULTS
This is because recent boundary changes bias the result in Labour's favour, according to something I read somewhere on that BBC site. Apparently Labour were rather better at lobbying the Boundaries Commission than were the Tories when these things were being established a few years back.