SO it transpires the British state does do contingency planning. Just occasionally. After two years’ heavy plodding down the via dolorosa of Brexit, David Mundell has finally acquired a strategy suit with a jelly pocket. The big court case is almost upon us, conveniently timed slap-bang in the middle of my summer holidays.

In April, Theresa May’s administration referred Holyrood’s Brexit Bill to the Supreme Court. Since then, the two sides have been exchanging legal papers behind the scenes, testing the arguments and running their lines. On July 24, the briefs and bundles will make their way to Middlesex Guildhall at Westminster for a major legal showdown in front of Supreme Court president Brenda Hale and six of her senior colleagues.

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The UK Government will try to persuade the court that Holyrood’s Continuity Bill is unlawful and should be politely deleted from the statute book. The Lord Advocate, by contrast, will defend the bill passed by 95 votes to 32 in the Scottish Parliament, arguing that MSPs were entirely entitled to introduce it.

As BBC Good Morning Scotland reported yesterday, there are dark emanations from Whitehall about the case. Nerves seem to be fraying in Dover House. Although Tory politicians are consistently bullish about their prospects in public, condemning Nationalist lawlessness and chicanery in passing the bill, Theresa May’s Government is reportedly wargaming for the possibility the justices find against them. None of the alternatives looks pretty or risk-free.

With their characteristic lightness of touch, the solution floated yesterday by UK Government outriders was subtle, diplomatic and rapier-like – the legislative equivalent doing light DIY with a mashie niblick. The leak has the Advocate General for Scotland’s condescending, politically tone-deaf paws all over it.

The strategy goes something like this. Who cares what the Supreme Court says? Who cares if the Brexit Bill was within Holyrood’s legislative competence? Honourable and Right Honourable members, Lords Temporal and Spiritual: join hands. Sod the MSPs. Let’s just repeal their Bill. Westminster is sovereign. Job done.

This, in fairness, is regarded as a controversial proposal in Whitehall. The Secretary of State for Scotland denied anything so dramatic was in the pipeline, win or lose the Supreme Court case. But as political solutions go, it has a kind of brutal simplicity.

A defeat in the Supreme Court won’t just be bad political PR for the UK Government. More pragmatically, it has considerable scope to leave UK Government Brexit policy in a mighty fankle with two concurrent Acts giving two sets of ministers concurrent powers over what laws remain on the statute book after Brexit. What if, for example, Michael Gove wants to knock out a provision Fergus Ewing wants to keep? How does all of this interact with the changes unilaterally made by Westminster to the Scotland Act? Does Westminster’s legislation impliedly repeal Holyrood’s, or vice versa? Even for the dabbling constitutional lawyer, these are the things synapse burnouts are made of.

When Theresa May’s law officers referred Holyrood’s legislation to the UK Supreme Court in April, the legal issues were new but fairly straightforward. The Lord Advocate argued that Holyrood’s continuity bill was within competence. He argued MSPs were entitled to anticipate Britain’s departure from the EU and to legislate accordingly. Presiding Officer Ken MacIntosh’s independent legal advice disagreed, holding that the bill was incompatible with EU law. So much, so simple.

Since then, everything has got considerably messier. Holyrood’s legislation is still on ice and can’t receive royal assent until the justices of the Supreme Court decide it is kosher. Westminster’s Brexit legislation, by contrast, has already been signed into law, distributing powers across government to chop and change the statute book after Brexit day.

The Secretary of State for Scotland was reduced to stammering denials yesterday, pledging to act “in accordance with the judgment of the court”, whatever it might be. But yesterday’s scuttlebutt is a powerful reminder that this is a Government we can expect to use every legal trick in the book to get their way.

The litigation over the Brexit Bill is just the tip of the iceberg. Murkier detail lurks in the devolution settlement, if you are an unscrupulous UK Government minister and care to go looking for it, or a paranoid law lecturer with a persecution complex and a “What Would Machiavelli Do?” wristband. Take Section 35 of the Scotland Act, which is blandly headlined “Power To Intervene In Certain Cases”. What does it do?

You know that Holyrood is built on a reserved powers line. If it ain’t on the list of issues reserved to London, Holyrood can legislate away to its heart’s content. But stray into reserved matters? The courts can step in and strike down your statutes. But Section 35 – which has never been used – does something sneaky on top of this.

It gives UK Ministers the power to spike Holyrood legislation if they believe any scrap or clause of it “would be incompatible with any international obligations”. It doesn’t matter whether or not the legislation falls squarely within Edinburgh’s legislative competence. The Secretary of State can exercise a pocket veto and wheech the bill from Elizabeth Windsor’s writing desk. Why might this matter in Brexit Britain? Imagine, if you can, that you are Liam Fox MP, Theresa May’s International Trade Secretary. You tour the world as Britain’s pre-eminent commercial traveller, grubbing around for trade deals with anyone who’ll take you.

Trade deals are treaties. Treaties create international obligations. And here we come full circle: international obligations give UK ministers power to spike Holyrood bills which don’t conform to the trade deals Liam Fox is trying to peddle .

Contemplate that, when you are gumming your rubberised American chicken, liberally soused in chlorine – or arm-wrestling a hormone-treated heifer from Nevada. Against this backdrop, some of the debate about whether post-Brexit powers will sit in London or Edinburgh and Cardiff looks like a dummy war.

It doesn’t matter if healthcare is a devolved matter, if Theresa May’s administration flogs it cheap to the terracotta Weeble in the White House. It doesn’t matter if food standards or fishing policy are dictated by Holyrood or Westminster, if the Tory salesmen decide the only way to keep “global Britain” in the pink is a Dutch auction of public services, environmental standards and planning policy.

To truss up Holyrood, David Mundell and David Lidington don’t have to attend interminable meetings with Mike Russell, or sit through Commons debates with Ian Blackford. They don’t have to rewrite the Scotland Act. All they need do is cut a series of deals in world capitals and use Section 35 to kibosh any Holyrood bill that threatens the free trade of our glorious new commonwealth.

The Brexit counter-revolutionaries aren’t kidding on. Devolved government has only a precarious place in their seagoing worldview. They didn’t care for it in 1998. They don’t care for it now.