Peter Hain thinks that Labour could pull of a surprise 1992 style poll victory: Hain
The difficult with this analogy was that John Major was a relatively new face in 1992 and, whatever else people thought about him, they generally found him personally likeable. Gordon Brown has been a major figure for thirteen years, initially in a 'dual monarchy' leadership.
Hain thinks the opinion polls are overstating the Tory lead because it's not 'cool' to admit one is backing Brown. No doubt when it gets to decision day some loyal Labour voters will reluctantly stick with the party, if only for fear of something worse. But it could also be seen as not 'cool' to be a Conservative.
What Dave Cameron has to be careful of is not talking the country down too much, either by predicting a Greek-style collapse of the public finances or over emphasising the broken society theme. If he can't give people some hope for a better future, they may not be enthused about voting for him.
Interestingly, Hain does admit that Labour has been losing ground in Wales, in part as a result of social changes. This is not insignificant given that the principality is somewhat over represented at Westminster: Cymru