So this guy has lost his car keys – dropped them somewhere – and he’s standing under a streetlamp staring down at the gutter when a friend sees him.

“Lost something?”, he asks.

“Yes,” the first man replies, “it’s my car keys. Think they must have fallen out of my pocket.”

“Is that where you dropped them?”, his friend asks.

“No,” he says. “But…there’s some light here.”

On the basis of a single opinion poll, some lively and well attended meetings, and a bunch of anecdotal evidence, it has been decided that we know the result of the Labour leadership election. But that single poll, and the packed meetings, are really the equivalent of the light being shone by the streetlamp in the old gag above. They tell us… something. But not, surely, quite how up to 600,000 people are about to vote.

Do we feel that pollsters have displayed particular expertise in identifying the true voting intentions of Labour-minded people recently? Can we be certain that this surge of new members and associates represents only one category of potential voter? I don’t think we can.

Only one leadership candidate has overturned expectations, created deep enthusiasm and generated momentum. And it should be a cause of some embarrassment to the other three candidates that it has taken the intervention of grandees and “big beasts” to focus minds more intently on the choice facing the Labour selectorate between now and early September.

The intense pacing of Gordon Brown yesterday was redolent of a severe if not unkind telling off from an exasperated head teacher, who finally felt it necessary to point out a few practical realities about electoral politics. To win, he said, it helped to be “credible, radical and electable”. The digs about Gordon never winning a general election as prime minister were misplaced. From 1992 onwards, Brown was perhaps the key architect of subsequent Labour victories: not the top salesperson, not the best leader, but the deepest and sharpest thinker.

Today, over 20 years after the so-called Granita pact between Tony and Gordon, we see the negative consequences of this duumvirate’s dominance over Labour politics in that time. No wholly convincing successor emerged. Only Alan Johnson has been spoken of consistently as a possible leader of the highest class, and he has apparently never wanted the job. Such (excessive?) modesty in a sense rules him out in any case, if he hadn’t ruled himself out already.

Supporters of Jeremy Corbyn are entitled to feel proud of what they have achieved. Their candidate has looked comfortable in his skin and sounded confident in his views. His understated fluency has contrasted with the less certain pitches being made by his two better established opponents, Andy Burnham and Yvette Cooper.

But I agreed with the thrust of Brown’s argument yesterday. And I don’t think some of Corbyn’s proposals – leaving NATO, reopening coal mines, possibly reinstating the old Clause IV – are going to win back the support Labour needs to regain lost seats.

Electability matters. If you thought that the caricaturing of “Red Ed” was bad, wait ’til you see what They will make of Corbyn. It’s distasteful, and unfair, but try this fantasy Daily Mail headline for size: “Meet Jeremy Corbyn: the Marxist friend of the IRA who tried to stop his kid from going to grammar school”.

None of these arguments will dissuade people who believe that, with Corbyn as leader, millions of previously disillusioned or apathetic voters will sprint back to polling stations, or that Middle England can be persuaded to give large-scale nationalisation another try. The manifest energy and enthusiasm for Corbyn is a rebuke to the other candidates. Something different is needed. But this?

The headline to this piece contains the opening lines to Queen’s classic hit ‘Bohemian Rhapsody’.

You’ll probably remember the next two lines:

“Caught in a landslide, no escape from reality…”

Reality will strike on September 12. I don’t think anyone is ready for what this all could mean.