Background: Boris Johnson has been re-elected moyor of London for a second term, beating Ken Livingstone by a narrow margin.

Boris Johnson is very lucky to be re-elected. Why? Because the biggest second-preference vote was “no-one”. If voters had used their form to the full, he could have easily lost. Here’s why:

First round votes:

Boris Johnson CON 971,931
Ken Livingstone LAB 889,918
Jenny Jones GRN 98,913
Brian Paddick LD 91,774
Siobhan Benita IND 83,914
Lawrence Webb UKIP 43,274
Carlos Cortiglia BNP 28,751

So, no overall majority, but Boris is ahead. However, count up the non-Boris, non-Ken votes and you have 346,626.

On the second preference votes, Boris won:

First preference votes Second preference votes Total
Boris Johnson 971,931 82,880 1,054,811
Ken Livingstone 889,918 102,355 992,273

But total up the second preference votes distributed – it comes to 185,235. That leaves 161,391 votes left “on the table”. Boris won by 62,538.

If those 161,000 votes had gone 70-30 to Ken, it’s Ken in City Hall. Quite a big ask, but do-able. There were lots of people who voted for the less-likely candidates for first choice, and then either didn’t put an “X” in the box for their second choice, or voted for another minority candidate. Perhaps they didn’t like either Boris or Ken – fair enough, but those 46 per cent have just lost the chance to make a big difference in the outcome of the election.

It shows how courting minority parties – just as Sarkozy and Hollande have had to do in France – can be the difference between winning and losing.