Tory MPs, this is the hour for heroes – not the hour to find David Davis's Brexit bumblings endearing

It’s as if a jovial Rotarian, bored with retirement, answered a production company advert for a reality show predicated on parachuting an amateur into the most technically demanding job British politics has ever known

If you were one of those Tory MPs struggling with an excruciatingly finely balanced decision – whether or not to defy the whip in the imminent votes on the EU Withdrawal Bill amendments passed by the Lords – perhaps this might tip the balance: David Davis doesn’t know what day of the week it is.

Metaphorically at least, this has been plain ever since Theresa May gave him the punishment job of negotiating the Brexit terms almost two years ago.

Now the man literally does not know what day it is, and should he be tempted to complain this slight is distortion, exaggeration or an outright lie, he’s reminded the impeccable source here is a certain David Davis.

Taking a break from yearnful gazing at the map of 18th century Europe on his office wall, Davis granted John Humphrys his first interview since the politician’s resignation threat melodramatics last week.

Davis’s intent was to reassure a fretful nation his negotiations with the EU’s Michel Barnier couldn’t be going more spiffingly. Predictably, this impression relied less on cogent argument – let alone hard fact – than one of those comically, cosmically misguided attempts to project confidence that have become his signature dish.

On many crucial Brexit issues, Humpo suggested, we are no closer to resolution now than on the morning the referendum result was declared. This seemed to tickle Davis, who chortlingly replied: “That’s just nonsense.”

Yet on the pesky question of the Irish border, the Brexit secretary is in such disarray he referred to the “backstop”, intended to ease Ireland through the transition period, as a) “something designed not to be used”, and for distinction, b) “something never to be used”.

In which case, one wondered, why bother humiliating himself by trying and failing to negotiate it in the first place?

That Barnier had just exploded another of this government’s fantasy masterplans, tweeting that the EU will never accept an end date to such a backstop, didn’t bother Davis a jot. “Well, this is a negotiation; let’s see,” he said, as he so often does. Yeah, and how’s the wait-and-see game working out for ya?

“You spent an hour with him … yesterday?” asked Humpo.

“Monday? Errr…” replied Davis, giggling again in his confusion. “Umm… I don’t know what day of the week it it is.”

Davis’s floundering remains mildly endearing. It’s as if a jovial Rotarian bored with retirement answered a production company advert for a reality show predicated on parachuting an amateur into the most technically demanding job British politics has ever known.

After selling his Lexus franchise for a tidy sum, this bluff old cove filled the time holding court in the golf club bar, pewter tankard in hand, banging on about the red tape iniquities of the EU, and how politics is really a common sense business best left to graduates of the school of hard knocks such as himself.

Then someone at Endemol rang with the news he’d been selected to be the secretary of state for exiting the EU, and could he get himself to Whitehall at once? What could possibly go wrong?

Now here he is joshing with Humpo as if this is just the best fun EVER – and going within minutes, from acknowledging the extreme complexity of the details of which he is supposedly master to admitting he doesn’t know what day of the week it is. He never sounded more than a Glenlivet chaser away from a chucklesome: “Why are you plaguing me with these questions, John? You might as well ask the cat.”

Are you not, to adapt Russell Crowe in Gladiator, reassured?

If not, and you happen to be a Tory MP wrestling with the dilemma about whether or not to vote to preserve some or all of the House of Lords amendments to the withdrawal bill, this may, as I said, be helpful.

The pressure on potential rebels must be pulverising. The government whips will have been unloading their full arsenal: bribery with hints of ministerial reward; blackmail via talk of deselection; appeals to tribal loyalty with warnings about “putting the Marxist maniac Corbyn in No 10, is that what you want?”; ritual accusations of treachery; and the traditional, thinly veiled intimations of physical force.

It would be glib to dismiss all that as negligible. However strongly these MPs believe the Brexit trajectory is a corkscrew spin, it takes real courage to resist. Understanding that treachery lies in voting with their consciences to the benefit of country and constituents is one thing. Acting on that, knowing they will be ostracised and savaged and might lose their livelihoods, is something else. Small wonder even as impressively independent minded a backbencher as Sarah Wollaston sounded a little wobbly at the weekend.

For all that the choice, if it wasn’t clear enough already, was clarified this morning.

It’s a toss up between devolving power over Britain’s future to a warring, clueless, paralysed, headless chicken of a government led – if that’s the word – by a PM who will not or cannot begin to define the post-Brexit EU relationship she wants; or taking the other side at their grandiose word when they blether about “reclaiming parliamentary sovereignty”, by giving the Commons some measure of control over the terms of departure.

Whatever day of the week it happens to be, it’s crunch time. There may not be a better chance for the Commons to limit David Davis’s capacity to giggle us to perdition. This is the hour for heroes.