Mandate - what mandate?

It can be assumed that those who voted in the recent election - at least those who thought about it - did so on the basis of what the various parties set out in their manifestos as their intended policies should they be elected. But on Wednesday we were presented with a document detailing what the coalition intend to do - which is a manifesto for which nobody voted, or indeed will have any opportunity of voting for - it is simply a fait accompli. Which raises the rather interesting question of what legitimacy the coalition have to pursue these policies - particularly those which did not appear in that form in either of their manifestos.