Is this a delayed reaction to the MORI and MRUK polls?

Yesterday morning I expressed surprise that the MORI poll had had so little impact on the mayoral betting markets. Overnight Saturday we had the MRUK survey, also showing Ken with a narrow lead, and at first the markets seemed to take it in their stride.

But this evening there has been a sharp move from Boris to Ken and it appears possible that the incumbent could find himself the betting favourite again.

Quite why this should have happened is not clear. There has been speculation that news of the next YouGov poll is about and that is affecting the betting. Maybe – maybe not. For even though the prices have moved the volume of activity has been fairly limited. Normally when there’s a leak that could affect an outcome like this and we would see a pile of money going on.

The chart above shows the Betfair prices expressed as an implied probability over the long period of this campaign.

I had been waiting for prices to move before going onto Boris again. I think I might take the cautious approach and wait to see what the next YouGov survey has in store. If Boris still has a clear margin then I’ll put more on. If not then I’ll consider my position across a range of betting.

Mike Smithson