We originally made our call on the London Mayor when Ken Livingstone was 21% ahead in the polls and when there was no threat that the Tory vote would be split by the rise of UKIP. As it has turned out the margin on first preferences was 7.46%. We thought it was going to be much closer and that the prices offered good value but in the end Ken came through.

Looking at it we can only conclude that it was Tony Blair’s brilliant move to announce the Euro Referendum in April that has caused this to go wrong. This took away a key platform in the Tory Euro campaign and was a main cause behind the extraordinary rise of UKIP which split the Tory vote substantially. The expected move of UKIP second preferences to Norris did not happen on the scale we would have hoped for.

We also misjudged the number of Tory and Lib Dem supporters in the Assembly elections who did not vote with their party ticket for the Mayor. In fact a large number voted for Ken Livingstone. For Ken to have secured these votes is remarkable and represents an extraordinary personal achievement. We estimate that one in six Tories and one in four Lib Dems in the Assembly elections switched to Ken for the Mayoralty.

Livingstone’s return to Labour did cause him to lose some support but not on the scale that we were predicting. By a long way he is the most successful Labour candidate in any election this week.

It is enlightening for future bets to look at how the pollsters did. The final YouGov poll on Wednesday had the following figures – compared with the actual number of first preferences.

Absolutely Certain to vote – Poll 37% Actual 36.95%
Ken Livingstone – Poll 35% Actual 35.7%
Steve Norris – Poll 32% Actual 28.24%
Simon Hughes – Poll 17% Actual 14.82%
Maloney UKIP – Poll 8% Actual 6.02%
Johnson GRN – Poll 4% Actual 2.99%
RESPECT – Poll 1% Actual 3.21%
BNP – Poll 2% Actual 3.04%
CPA – Poll 1% Actual 2.17%
Others – Poll 0% Actual 0.85%

The major overstatement was the Norris vote that was 3.76% below the poll and Hughes that was 2.18%.

The YouGov “certain to vote” figure was precise and this should be a good pointer to future analysis of YouGov polls. But the substantial overstatement of the Norris vote could cause questions to be raised about internet polling.

One things is certain for YouGov – their 4% overstatement of Norris in this election was not on the same magnitude as the 21% overstatement of Ken’s margin by ICM in at the 2000 Mayoral Election.

On Sunday the Euro Election results should be out and the second be test for YouGov will take place. Will YouGov’s suggested 21% national share for UKIP prove accurate?