Those that read the Evening Standard will know that YouGov has a new poll out on which Labour hopeful would make the best candidate for London Mayor.

As we might expect, the Standard has run with the line ‘David Lammy leaps to second place in Labour’s mayoral candidate race’ but we should be careful when jumping to conclusions.

Once ‘don’t knows’ and ‘none of these’ are excluded, the sample size for this poll is just n=460. This is a perfectly reasonable sample size for a poll of this nature but it does lend itself to sharp fluctuations in poll ratings. For example, Dianne Abbott jumped seven points in April but then fell ten in this poll. Also, with Lammy and Kahn one point apart, margin of error comes into play too. Put simply, it is a good poll for Lammy but time will tell whether it is a genuine surge or not. After all, statistically speaking, it is not clear he is really second anyway.

So what should we make of this poll? Well, with 31% of Labour supporter’s undecided it’s still all to play for. That said, Tessa Jowell is clearly in a very strong position. No clear alternative candidate has emerged to challenge her and there are some very good numbers for her when we dig deeper into the data. She commands a 21 point lead amongst women overall and a 35 point lead amongst the over 60s (who we know will vote). She also actually performs proportionally better among Conservative voters than Labour suggesting that she possesses the ability to reach out to voters she will need to win back for Labour to take the Mayoralty from the Conservatives.

If there is a crumb of comfort for her opponents, beyond the ‘don’t knows,’ it is that this poll merely looks at a cross-break of those voting Labour in 2015 rather than members specifically.

Given the apparent momentum in the Corbyn campaign for leader, perhaps one of these candidates can emerge as a genuine ‘leftist’ alternative to Jowell. However, unless one of Abbott, Khan or Lammy were to withdraw and support one of the others, it is hard to see her losing her front-runner status any time soon. Given Labour’s electoral system allows for the allocation of preferences and none of her three main opponents consistently lag behind in fourth place, it is not clear why any of them would drop out and what they would gain by doing so.

So, for now, this race is very much Tessa Jowell’s to lose. Labour really needs to win an election soon and perhaps she is its best chance for the time being.

Keiran Pedley is a polling and elections expert at GfK and tweets about politics at @keiranpedley