Thank God David Davis has finally clarified what Brexit will mean for Britain – for a second there I was worried

The only thing worth knowing about the movie business, a great Hollywood scriptwriter famously observed, is that no one knows nothing. If he is still taking commissions at 85, William Goldman would be the obvious choice to write Brexit: The Movie. Approaching three months after the referendum, the PM is uneasily pictured on the outskirts of that G20 group photo in China… and still NO ONE. KNOWS. NUFFINK.

Does Brexit mean leaving the single market entirely, mostly, a fair bit, or not really at all? Who can say? Does it mean ending, partially restricting or barely tinkering with freedom of movement? Not a clue. How long will it take to negotiate trade deals with the EU, the US and other nations, and how punishing might the terms be? Go figure. Will British expats retain the right of residency in EU countries? Beats me.

There are scores of other intriguing questions raised by the June vote, and to all of them the official reply may be paraphrased as follows: you might as well ask Larry, the Downing Street cat.

For every human ostrich to whom this ignorance is bliss, countless souls will find the uncertainty unnerving. Even the zealous Leaver who felt imprisoned by Brussels may be feeling a little like the paroled lifer whose initial rush of exhilaration is cauterised by the first unfamiliar blast of sunlight. Brooks in The Shawshank Redemption, for instance, who cannot handle life on the outside, and hangs himself.

Yet as we stumble about getting nowhere in the darkness, give thanks for one shining beacon to illuminate the path. What, David Davis was repeatedly asked in the Commons this week, does Brexit mean? Brexit, replied the Brexit Secretary, sampling the PM but speaking with the unique insight his portfolio confers, means Brexit.

If gnomic impenetrability is what you want from any means-related slogan, Brexit-means-Brexit must be the best ever. Beanz Meanz Heinz was pretty good in its day, at least when you first heard it in a TV advert. What the naked ear took for “beans” could have referred, after all, to string, runner, kidney, borlotti or any other member of the bean family. Only when you saw it written as “beanz” did that “z” remove any doubt that it was a Heinz haricot bean in tomato sauce, and all the fun went out of it.

Another contender from yesteryear was “Love means never having to say you’re sorry”, the tagline from the film of Erich Segal’s weepy novel Love Story. That sounded unfathomably deep and meaningless on first acquaintance. Then it struck you that love means having to say sorry all the time, frequently for offences you haven’t committed – and in catchphrase terms, being diametrically wrong and arrant cobblers ain’t a patch on meaning nothing.

The biggest loser of the “means” genre, I think, is a staple of the short-tempered parent. Admittedly, “no means no” seldom works. Overheard in the supermarket sweetie aisle, it tends to be the prologue to, “Oh, all right, then, have the f****** Haribos, see if I care if you get dentures for your 10th birthday.” Yet its fatal flaw is its clarity. “No” in this context can only mean “no”. It can’t possibly mean “Yes”, “Maybe”, “Noel Edmonds’ scrotal sack”, or, “Watch yerself, missus, or I’ll move that Nissan plant from Sunderland to the outskirts of Zagreb.”

To his credit, David Davis understands that a catchphrase’s paramount aim is to bamboozle. Bruce Forsyth never grasped this, which is why he’d be such a hopeless Brexit Secretary. When he asked, “What do points make?”, the only possible answer was “Prizes!” Ditto with “Nice to see you…” In a political climate which treasures opacity, Brucie would be way out of his depth.

If “Brexit means Brexit” is genius – and it is – this has less than nothing to do with the factual accuracy which is such a wickedly devalued currency in the context. “John is John,” Tony Blair said of Prescott after he biffed the eggman, and that also was true. “Black is black,” sang Las Bravas in 1966, before adding that they wanted their baby back. Again, no argument there.

No, the cosmic brilliance of “Brexit means Brexit” is that, unless or until defined by reference to more than itself , Brexit potentially means anything, and therefore means absolutely nothing.

With government and country trapped in this curious stasis while we wait for Brexit to take corporeal shape, several indicators suggest the economy is performing far better than doomsayers predicted. This is great news, and long may it continue, though the Prime Minister is less optimistic than those pro-Brexit newspapers which are prone to premature self-vindication.

Theresa May warns of serious trouble ahead. With Obama and the Japanese issuing doomy warnings, Lloyds of London threatening to jettison its “of London” by relocating, and other alarming portents, we can probably trust the PM on that.

So it is that, even as bullish Brexiteers greet the short-term growth in consumer spending and the construction sector as definitive proof that the promised land is in view, I can’t help recalling the end of William Goldman’s greatest movie. “For a moment there, I thought we were in trouble,” a relieved Butch Cassidy tells the Sundance Kid after the outlaws apparently cheat death by hiding in a disused fort. In the next shot, they stroll out into both the sunlight and the gunfire of the entire Bolivian army.

* This article has been amended. It originally referred to Wiliam Goldman as having died. We are pleased to confirm he is still very much alive. 13/9/16