In case people aren't aware of how difficult Cameron remaining in No 10 is. This FT analysis shows the barrier they are up against:
http://www.ft.com/cms/s/0/43838f80-e...#axzz3XZLOtGXy
In case you don't think that's legit try this BBC game:
http://www.bbc.co.uk/news/election-2015-32336071
It's really hard to see how the Conservatives can do it unless they or the Liberal Democrats hold onto a lot more seats then they're currently projected to do so. Even then the LibDems might be minded to go with Labour.