Back in November 2010, I wrote in my NS column:

One of the most frustrating aspects to writing a regular column on British politics is having to challenge the conventional wisdom in which so many of our leading broadcasters, reporters, columnists and now bloggers seem to bathe. Groupthink abounds inside the Westminster village. Lazy assumptions proliferate like weeds.

Take the run-up to the general election. For much of 2009, political correspondents and pollsters, columnists and commentators queued up to predict the size of the impending Tory landslide. Would it be double-digit? Or triple-digit? The idea that the Tories might fail to win the election outright was, to put it mildly, considered "unconventional".

I also noted how I had been

mocked by some of my peers for daring to suggest on these pages, in June 2009, in the wake of Labour's humiliating defeat at the European elections, that the Tories' poll ratings were "soft" and Labour still had "a fighting chance of a hung parliament at next year's general election".

So I couldn't help but smile when a press release from YouGov, with the results of their latest poll on London's forthcoming mayoral election, dropped into my inbox this morning.

It revealed that Ken Livingstone had overtaken Tory incombent Boris Johnson in the race for City Hall, with the Labour candidate taking a narrow 51-49 lead.

Ken takes lead over Boris in race for Mayor

announced the headline in the Evening Standard.

Refreshingly, YouGov president Peter Kellner openly confessed:

The facts have changed, so I have changed my mind.

Throughout last year, I regarded Boris Johnson as the likeliest winner of London's coming mayoral election. YouGov and other pollsters showed consistently that around one-in-five Labour supporters would desert Ken Livingstone and vote for Boris. From Labour's viewpoint, London began to look alarmingly like Scotland, where Alex Salmond won his stunning victory last year because one in five normally Labour voters switched to the SNP.

Our latest poll tells a different story. We find a five-point swing from Boris to Ken. Last June, Boris enjoyed an eight-point lead (54-46%); now Ken is two points ahead, by 51-49%. Allowing for sampling error, the race is too close to call.

Will others in the Westminster village and the commentariat now join Kellner in "changing" their minds? Will they now admit that Ken Livingstone has not just a chance but a fighting chance, a good chance, of winning May's mayoral contest? Up until this point, the "lazy assumption" - even among some centre-left journalists - has been that Boris Johnson will walk it, that he has the election sewn up. (Remember all those journalists and columnists who were so keen to crown Cameron as PM in 2009 and January-April 2010, and assume a landslide majority for the Tories was in the bag?)

YouGov's latest poll suggests that those of us who were sceptical about such claims had good reason to be. Admittedly, it's a single poll and there's all the usual stuff to note about outliers, rogues, sampling errors and the rest, but I suspect more and more polls will start reflecting Ken's start-of-the-year "surge" in the coming weeks.

As the Standard notes:

Moreover, the three issues that Londoners regard as most important are those that Mr Livingstone has campaigned hardest on: tackling crime (picked by 42 per cent), improving transport (41 per cent) and easing the cost of living (33 per cent). Only four per cent think promoting London abroad, a regular Boris theme, is a priority.

The energetic and focused Livingstone is hitting the right issues - and hitting them hard. There is a lesson for his party leader here: Ed Miliband shouldn't be trying to cover and campaign on every issue, in detail, all the time, but picking those few issues that voters care about and that Labour has leads over the Tories on - for example, jobs and the NHS - and hitting them hard, in speeches, interviews, photo-ops, etc, again and again and again.

There's also the intriguing issue of Livingstone's personality, his authenticity: in the modern political era, few candidates for high office are harmed by being themselves. In fact, the reverse is true.

Speaking of Ed Miliband, this latest poll will provide a much-needed boost for him and his aides too, after a horrid start to the year. If Livingstone wins against the odds in May, and London goes Labour, expect Miliband and his supporters to spin it as a victory for his leadership and his political agenda - and vote of no-confidence in David Cameron. If Ken loses to Boris, however, expect whispers about the future of Miliband's leadership to get louder. Much louder.