I don't mind it when politicians dissemble, or even when they subject the truth to a wind tunnel test to see how much stress and strain it can take. What I do object to is when a party hack lies through his teeth and then dissembles to try and defend his lie. That's what Jim "Spud" Murphy did on Newsnight last night.
Spud claimed that "the biggest party gets to form the government," and that is just not true. The man who is sent for by The Queen to form Her government is the man who can command a majority in the House of Commons. Normally that is the largest party because that party has a majority, but it is the majority that matters, not where it comes from. Spud was at it again when he said that "it isn't the case that you add up the party that comes second, the party that comes third, the party that comes seventh," because that is exactly what can be done if those parties agree to vote together against the single largest party that does not have a majority.
Cameron as leader of the largest single party could try to hang on, but if Labour and the SNP have a majority of the seats between them and vote against him then he will have to resign. The Queen is then constitutionally bound to send for Ed Miliband if he can offer Her a government that commands a majority in the Commons.
If you want the Tories out, and want to see a government more to your liking come in, then you should ignore Spud's porkies and vote Labour in England and SNP in Scotland.