As I said previously, it will be something that the pollsters can point at if they are wrong, just as they did with England's World Cup exit in 1970 and the Sheffield Rally in 1992.
I think unless there's some kind of unexpected blowout in either direction, only Mori seems to be consistent in their sizable Con leads. What is interesting, looking at 2010, the late polling, generally got the Lab and Con votes in the ball-park with both of them slightly underestimated.
Average of the last 15 polls of the 2010 cycle
CON: 35% - result: 36.9%
LAB: 28% - result : 29.7%
LD: 27% - result: 23.6%
OTH: 9% - result: 9.8%
The average of the last polls - 4-5 May 2010
CON: 36% - result: 36.9%
LAB: 28% - result: 29.7%
LD: 27% - result: 23.6%
OTH: 9% - result 9.8%
Now, what is that suggesting to me? Again, my knowledge of a lot of UK electoral idiosyncrasies is wonky... but...
With both parties sitting pretty consistently in most polls with numbers around 33-35% for each... my expectation is that we'll probably see results somewhere in that ballpark. But... it does make me think that the other parties will be considerable variations in the performance on the day versus the polling. If anything, my gut feel is that the LD are being underestimated with UKIP and to a lesser extent the SNP being over-estimated. Of course, multi-party elections with FPTP across over 600 constituencies means we're all probably wasting our time