The latest YouGov poll  on the London mayoral election won't make happy reading for Team Ken. The poll puts Boris on 48 per cent among those who are certain to vote, with Ken trailing on 41 per cent. Boris's lead has risen by four points since February  when he led by 45 per cent to 42 per cent. In a straight fight between Ken and Boris (excluding "Liberal Democrat candidate"), Boris would win by 49 per cent to 41 per cent.
Significantly, Boris leads among Lib Dem supporters - the swing voters in this contest - by 41 per cent to 30 per cent. Worryingly for Ken, just 63 per cent of London Labour voters would vote for him were an election to be held tomorrow, with nearly a fifth (19 per cent) backing Boris.
After failing to win back control  of the Scottish Parliament from the SNP, it's important for Labour and Ed Miliband that Ken succeeds in London. But, as things stand, that is looking increasingly unlikely. The fact that Labour is leading in London by 51 per cent (+3) to the Tories' 32 per cent (+1) will be cited by some as evidence that an alternative candidate could be performing better.