BETTER one sinner repenteth – never mind 13 – but I’m still baffled. All politicians like their ferrets reversed – or at least, conveniently reversible – but over the past couple of weeks, the stoats have been swinging around the rafters of Holyrood particularly violently.

When David Davis first tabled his Brexit Bill, David Mundell promised that the UK Government’s proposals to untangle us from the EU would not represent “a power grab, but a power bonanza” for the devolved parliaments of the United Kingdom. In place of centralised EU regulation, he assured us, London, Edinburgh, Cardiff and Belfast would all be able to track their own courses, to “take back control” if you will. That was the theory anyway.

But predictably enough, the Bill produced by Mrs May’s Government instantly ratted immediately on this aspiration. Almost 20 years after devolution, given two decades to get comfortable with distributed decision-making, and four Holyrood sessions to acquaint themselves with the notions of negotiated political co-operation and shared powers – zero, zilch, nada.

The EU Withdrawal Bill proposed to leave Holyrood and its sister assemblies across this country all trussed up by EU law, while giving Westminster and Whitehall free reign to strip out, redefine and re-regulate across the territory formerly occupied by the European institutions. If they didn’t like it? Edinburgh, Cardiff and Belfast would have to lump it. The Bill is a monument to Whitehall’s limited constitutional imagination. Its animating principles are all too familiar: top down, we decide, you get only what we’re prepared to give you.

The Labour First Minister of Wales was unimpressed. So was Nicola Sturgeon. They called the Bill out for what it was – a small nuclear bomb casually planted under devolution by a neurotic central government, incapable of letting go. Cue a majestic degree of harrumphing from the Tory benches. As recently as September last year, the Secretary of State for Scotland took to the international stage to scoff at the Scottish Government’s anxieties, lecturing presumably baffled pooh-bahs in Paraguay about how the UK Government had “been accused by the Nationalist government in Edinburgh of a power grab”, of “using our exit from the EU as an opportunity to centralise power at Westminster”, said Mr Mundell, “That is simply not the case.”

The same month, Tory MP Ross Thomson cried “blatant scaremongering”. In Holyrood, Ruth Davidson’s deputy characterised the First Minister’s disquiet as hopping on to a “soap box to promote a grievance agenda”. As soon as the Brexit Bill was published, unease about its implications for Holyrood were consistently denounced by Conservative and Unionist politicians in Holyrood as yet another fever dream spawned from the swampy, paranoid imaginations of madcap Nats, bent on “petty politicking” with the issue.

This was pretty unforgiving as political lines go – David Cameron’s dream of “the respect agenda” between governments in these islands crumbling as quickly as his political career – but it had the merit of fitting neatly into standard Scottish Tory world view, which seems crammed full of devious Nats with a one-eyed focus on independence, and the cynicism to use any tool to promote it.

But then? Then, something miraculous happened to the Tory caucus in Holyrood. Something changed – and nobody seems to have an adequate explanation for this dramatically reversing political ferret. Last week, Holyrood’s Finance and Constitution Committee concluded that Westminster’s Brexit Bill “is incompatible with the devolution settlement in Scotland”. This conclusion was backed not only by SNP, Labour and Green members, but also by the three Tory MSPs on the committee, who had so recently been burbling furiously about nefarious Nationalist politicisation. Having slipstreamed – belatedly and quietly – in behind the First Minister’s position, Ruth Davidson has called for Clause 11 to be “replaced and rewritten”.

Which is all well and good. But having heaped months of scorn over folk trying to defend the integrity of devolution, having cynically attributed the worst of motives to people advancing substantive concerns about her Government’s actions, someone seriously needs to ask Holyrood’s opposition leader what changed her mind on something so fundamental.

First, let’s be cynical. Foreseeing the challenges of ramming a devolution-unfriendly Bill through the Lords, you might think the Scottish Tories chose deftly to rush to the aid of the victor, cynically repositioning themselves – not as Theresa May’s stormtroopers, but in the old role of the Tory wet, framing themselves as moderating the excesses of Tory central office.

Alternatively, try to be charitable. Perhaps the weight of evidence flipped the Scottish Tory view. The professors Holyrood heard from were united. Richard Rawlings argued that “the sooner Clause 11 of the Withdrawal Bill is cast aside, the better”, arguing it embodied “an unthinking form of ‘Greater England’ unionism, which assumes only limited territorial difference” between the different jurisdictions which make up the UK. Michael Keating characterised it as Westminster taking “back powers for what appears merely to be reasons of convenience rather than of principle”.

Even ex-Whitehall panjandrum Jim Gallagher agreed the Westminster Bill was “not consistent with the UK’s territorial constitution”, regarding the clause as only defensible if it was tagged with a sunset clause to kill it off in short order. The committee unanimously rejected even this qualified defence of the Davis Bill.

Despite his reputation as a hectoring and partisan horror show, Tory MSP Adam Tomkins isn’t a cardboard cut-out politician and has a keener – and heretical – sense of the limits of old time Diceyan sovereignty, which says that Westminster can do whatever it likes and everyone else can go hang.

His problem is the constituency for this kind of thinking seems vanishingly small in his party’s Westminster delegation.

The Scottish Tories are still struggling to speak with one voice. This week David Davis listened to Joanna Cherry’s questions with all the grace of a baffled terrapin. The Secretary of State snapped and hissed at reasonable queries about the missing amendments, first insisting that Ms Cherry should direct her questions on his Brexit legislation to the Scottish Government, and then to the unfortunate Mundell, while boorishly insisting “the Bill is mine so you must assume I have responsibility whatever else happens”.

The Secretary of State having failed to turn in his homework in good time, we now have to put our faith in the scarlet plantations in the Lords to do right by devolution in Wales, Northern Ireland and Scotland. That thought doesn’t fill me with confidence, but the critical point remains this: there is a world of difference between the imposition of Westminster rule and working together towards shared goals.

A gulf separates subordination and real constitutional fellowship between the different parliaments in these islands. As David Mundell has – achingly slowly – come to realise, Clause 11 isn’t the only way to deal with the 111 or so powers which Brexit leaves sloshing around the UK constitution, looking for a home. But let’s not caricature. When it comes to devolution, the Conservative Party is a kaleidoscope of more progressive instincts and profoundly reactionary tendencies.

As Brexit snakes on, and as the Tory tribes go to war, the Scottish Government has remained commendably clear. We’re not prepared to be pushed around, Secretary of State – but we’re prepared to talk. Ruth Davidson tells us she wants to be First Minister. As her party ferrets all across the landscape, sallying forth to lob grenades and then furtively retreating, Ms Davidson might ask herself this: what self-respecting devolved government could do less?