Barmy, a friend said over lunch on Thursday in the giant glass bubble with rented trees at Westminster that they call Portcullis House.

“Bizarre,” I replied. “Inexplicable.”

“Selfish,” another friend chimed in.

“Yes, ego-tripping. Grandstanding. Typical.”

“Attention-seeking,” a colleague said to me, after lunch, on College Green outside the Commons entrance.

“A stunt,” I said to anyone who would hear, observing camera crews setting up all over the lawn for on-the-spot two-ways about the resignation of David Davis.

Cameras were soon in action as well-known television faces interviewed well-known Westminster pundits wherever one could be found. By late afternoon, in and out of the Portcullis glasshouse, voices could be heard barking at boom mikes, braying over coffee cups, and spitting into mobile phones: “Barmy!” “Selfish!” “Brainstorm.” “Inexplicable.” “Vain.”

I distrust clichés such as “Westminster village”, but there are occasions when they fit. Within the space of an afternoon a relatively small number of people - MPs, broadcasters, journalists, party hacks - gathered within a relatively confined space and, communicating mostly with each other, worked each other up into a clear, sharp and settled judgment on the question of the hour. By now it was almost unanimous. The judgment was conveyed electronically to the offices of the national press, bouncing back at Westminster in the form of vituperative editorials and opinion columns by dawn the next morning.

Thus, by echo, a single opinion reinforced and magnified itself. David Davis had acted eccentrically. He had acted independently. He had acted dangerously, self-interestedly. He had been profoundly unhelpful to his Tory team.

None of these accusations do I dispute. Had I been one of Mr Davis's confidants, I would have tried hard to dissuade him from taking a risky and exotic stand that makes doubtful constitutional sense, and can alter little about his country except the way that it sees him.

But there is one big assumption that I do dispute - that the electorate will not be impressed. Theirs is a voice that was not heard, asked for or even mentioned as Westminster, Broadcasting House and Fleet Street whipped themselves into a frenzy on Thursday afternoon.

Although I wouldn't bet on it, this Tory maverick may touch a surprisingly popular nerve.

Raw courage may be admired, simply as a human quality. Look at George Galloway's weird majority in 2005. The public is heartily sick of politicians who hedge, duck and scuttle for cover whenever it would be awkward to take a stand. Perversely, many who disagree with Mr Davis about the 42-day business may respect him the more for choosing to make himself vulnerable (as they will see it) to their disapproval. “You've got to admit he's got guts,” people may say.

The risk for Mr Davis is not that he will be seen as reckless, but that he will be seen as vain.

His instinct, too, to seek a popular mandate may be admired. Unpolitical people are more bothered than political people realise that Britain's Prime Minister has been elected neither by the country nor his own party, and spectacularly lost his nerve about putting that right. A passionate minority in Britain feel the same about a referendum on the Lisbon accord. The idea that our politicians don't care about (or fear) what the public think runs deep in our popular culture.

On the narrower issue of 42 days, a substantial minority will admire Mr Davis tremendously for making it an issue at all. The Lords, who may kill this measure, are wholly unelected. Everyone knows it passed the Commons only by the whips' arm-twisting, designed to subvert our elected representatives' own judgment. Mr Davis could appear to be trying to remedy these democratic deficits.

He will aim to widen the argument to a large, cloudy lament about state surveillance, official nannying, prying and snooping, and a thousand small encroachments on the general liberty. This strikes a chord more widely. We who take a professional interest in politics may accuse Mr Davis of conflating distinct issues. But the public does conflate.

So, although Mr Davis's motives may be suspect, the vanity palpable, the distraction unhelpful, and even if the constitutional case for a non-referendum referendum makes no sense at all, I am not quite confident that is how the voters will read the story. Fable it may be, but they may read a tale of one man, alone, with all Westminster scoffing, walking into the lions' den to risk everything and test the will of the people.

If that is how voters see it, then it is important for David Cameron, whatever his private furies, not to end up on the wrong side of this argument. Mr Davis could even appear as a martyr, a man of the people from the council estates who broke the big boys' rules in the Westminster game. Etonians must tread with care. David Davis versus the Right Hon David C. Goliath?

And if leading Tories vent their anger in public, they play straight into a developing media story about Tory division. Were I Mr Cameron I would try to sound as if I really meant the line that he tried (but with insufficient conviction) on Thursday - that David Davis had done a brave, daredevil thing that I probably wouldn't have recommended; but that I admired his courage and backed his stand for liberty; and now that he had gone into battle he would find me and all my Shadow Cabinet on his side - and by his side in the streets and lanes of Haltemprice & Howden.

And I would not allow an impression to arise that Mr Davis is to be banished to the back benches. If his venture flops and he creeps back to Parliament after an insultingly low turnout in a farce of a by-election, such may be his fate. But what if the contest catches fire? Mr Cameron does not want to look as though he has been forced to re-employ a rival he hoped to see squashed, still less to face a legitimised and now bitter challenger on the back benches.

As for Labour, they should think before they crow. At the dispatch box Gordon Brown has attacked Mr Cameron in grave terms for flouting the popular will on 42 days; now a man has taken up that challenge and submitted himself to the people's verdict. If (as I expect) Labour refuses to give Mr Davis a fight and instead sneers from the sidelines, how will that look?

In the Portcullis glasshouse we are so used to circumspection that when a politician acts in a daredevil way we don't quite know what to make of it, and so condemn.

Mr Davis may have an eye to a different Britain. His actions betray an element of madness, but madness can be dangerous. His party will hope that by this time next week the storm will be over and David Davis will be a diminished and negligible coxcomb fighting a silly by-election. That is the likelihood but not the certainty. For the Tories, and for the moment, it is worth keeping him on side.

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