The August ICM poll for the Guardian is out tonight and has topline figures of CON 31%(-3), LAB 38%(+5), LDEM 12%(nc), UKIP 10%(+1). It’s a much higher Labour lead than ICM have shown of late, their polls for the last few months have been showing Labour and Conservative essentially neck-and-neck. As ever, don’t read too much into a single poll, it might be the start of a broader Labour increase… or may just be normal sample volatility.

The poll also asked how people would vote with Boris Johnson as Tory leader, and found the Tories on 34% (3 points higher), Labour on 37% (one point lower) and UKIP two points lower. This is different from the conclusion to the YouGov poll at the weekend that showed virtually no change from a Boris leadership, but it appears to be the result of slightly different approaches to asking the question. Compared to their standard question, bot h YouGov and ICM found Labour’s lead reduced by three points when you asked how people would vote with Boris as leader. However, the difference is that YouGov also asked a control question of how people would vote if the leaders remained Cameron, Miliband and Clegg, and that also reduced the Labour lead by 2 points, accounting for much of the apparent “Boris difference”.

That said, I wouldn’t take “How would you vote with X as leader” questions too seriously anyway. People are rubbish at answering hypothetical questions, and here we’re expecting them to say how they’d vote with X as leader without knowing what changes X would make, what priorities and policies they’d adopt or anything else about what an X leadership would look like. They can be useful straws in the wind, but really, they are no more than that.

UPDATE: Meanwhile the Sun have just tweeted the daily YouGov poll: CON 33%, LAB 37%, LD 8%, UKIP 12%