We tend not to be too poll-obsessed here at LDV – of course we look at them, as do all other politico-geeks, but viewed in isolation no one poll will tell you very much beyond what you want to read into it. Looked at over a reasonable time-span and, if there are enough polls, you can see some trends.

Here, in chronological order, are the results of the most recent nine polls since our last round-up on 28th March:

Tories 43%, Labour 32%, Lib Dems 18% – ICM/Telegraph (6th April)
Tories 39%, Labour 33%, Lib Dems 17% – Populus/Times (8th April)
Tories 44%, Labour 28%, Lib Dems 17% – YouGov/Sunday Times (13th April)
Tories 40%, Labour 30%, Lib Dems 19% – Populus/Mirror (20th April)
Tories 39%, Labour 34%, Lib Dems 19% – ICM/Guardian (21st April)
Tories 44%, Labour 26%, Lib Dems 17% – YouGov/Telegraph (24th April)
Tories 40%, Labour 31%, Lib Dems 19% – Mori/Observer (27th April)
Tories 39%, Labour 29%, Lib Dems 20% – ICM/Telegraph (27th April)
Tories 40%, Labour 26%, Lib Dems 20% – YouGov/Telegraph (29th April)

Which gives us an average rating for the parties in April as follows, compared with March’s average:
Tories 41% (n/c), Labour 30% (-1%), Lib Dems 19% (+1%)

In previous round-ups I’ve complained about the erratic vote share ascribed to the Lib Dems, with (for instance) YouGov showing the party polling consistently lower – and outside the margin of error – compared to ICM. Yet in April all four polling companies had the party within the range 17-20%: whether this is a reflection of a firming up of Lib Dem support, especially in the run-up to local elections – or pure chance – we will discover in the weeks to come.

Instead, it is now Labour’s turn to be turning in an erratic polling display, with four polls showing them below 30% (a truly disastrous showing). Within three days, two polls showed the party at 26% (YouGov) and 34% (ICM): some difference. Quite what the reason for this sudden turbulence might be, I’m not sure. I’m guessing it’s a reflection of the ‘certainty to vote’ criteria which different polling companies apply in order to reflect what voters will actually do in the polling booth (and whether they’ll bother voting at all).

Much was made of the Tories’ huge leads over Labour during April: yet their average rating remained stuck at the 41% level. The large differences between the parties have been a reflection of Labour weakness, rather than Tory strength.