Ken Livingstone's supporters have blamed lots of people for his defeat in 2008.
The Evening Standard, Gordon Brown and outer Londoners have all received their share, but there's one bigger issue that I think they've overlooked.
I've always thought that the £25 gas-guzzler charge did more to damage his chances last time than any other policy.
In theory the charge was a good idea, and would only have affected a relatively small number of drivers.
But I suspect the number of people who wrongly thought they were going to be hit by the charge, was much higher.
What was in reality a localised charge on only the most polluting vehicles, quickly became seen by many as a London-wide tax on all larger cars.
Londoners of all classes, both inner and outer, saw the looming prospect of a £25 charge and jumped straight into the arms of Boris.
This can be seen in the polling done at the time.
One poll (commissioned by Ken) gave lots of detail about the scheme including which vehicles would be affected and which would be taken out of charging altogether.
After receiving all of this information, the poll showed widespread backing for the scheme.
However another poll which asked simply about "increasing the congestion charge to £25 a day for higher polluting cars” found much narrower support at 41% to 39%.
And another more detailed poll showed that 74% of Londoners and 65% of Ken's voters thought the proposed £25 charge was too high.
That's a lot of opposition to what was Ken's big new policy for a third term.
And sure enough, the next poll conducted after this policy was announced showed Boris Johnson in the lead for the first time. A lead which Ken never recovered.
Of course there's no way of knowing for sure that it was the gas-guzzler charge that did it for Ken.
But in a close election, it is exactly the kind of issue that could swing the balance.
In an interview today, Livingstone tells the Guardian that the gas guzzler charge is "definitely an idea we will revisit."
If I was him, I would make it a short visit.