The story of Brexit is not one of grand strategies executed to perfection. That, perhaps, is why so many exhausted people have been keen to read strategic genius into the positions taken by Boris Johnson and his coterie – especially his adviser Dominic Cummings.

But part of their plan – such as it is – has involved crashing through the institutions of British public life. They may have overlooked that the institutions can fight back.

The Supreme Court ruling means the prime minister can not escape scrutiny or direction from Parliament via prorogation. Not now, not in future. It takes a weapon from the executive’s arsenal.

At some point deeper into this crisis, MPs may – for example – want to install an interim prime minister, and this legal protection may prove critical to their ability to do so.

But the immediate effect of the Supreme Court ruling, as dramatic as it was, may be less than meets the eye in the short term. The direct consequence is to create new sitting days in parliament – but it does not change the voting arithmetic there. So there are limits to what the rebel faction of 21 MPs expelled from the Conservative party, who hold the balance of power in the Commons, can do with the time.

We know their ambition is to prevent a No Deal Brexit – which means trying to direct the government’s course with anti-No Deal legislation while also stopping an immediate general election, which could close parliament at a critical moment.

But what is the strategy? One of the rebels’ generals has told me they intend “guerrilla war”. They can pass so-called “Humble Address” motions to seek documents. They can table “urgent questions” – short-notice questioning sessions which force ministers to appear for grilling.

They cannot go much beyond that – the rebel alliance still agrees on too little with other blocs in Parliament (or one another). But this extra space can be used to check the stitching on the anti-No Deal Act they have already passed.

The so-called Benn Act compels the government to seek an extension to the UK’s EU membership in the event that Britain looks likely to leave without a deal – but there are some concerns about whether it may have a few holes. MPs have a chance to satisfy themselves that it is tight enough to prevent a No Deal Brexit.

The bigger consequences, though, are political. No-one will lose their job over today’s ruling – least of all the prime minister. But it diverts the flow of the competing Brexit narratives a little.

On the one hand, it plays to the “screw the elites” narrative, of which we know Cummings is so fond. Hence, perhaps, the prime minister’s response to the unanimous verdict of the Supreme Court of the United Kingdom: blunt disagreement.

But look back at the past few months. The prime minister surely did not expect to have lost all six of his votes in parliament, to lose his parliamentary majority, to withdraw the whip from 21 Tories, or to have a member of his cabinet resign – let alone his brother.

Johnson has now been embroiled in a scandal about the improper use of public money – and, week after week, more evidence emerges that he is not quite as good at dealing with hoi polloi as we had been led to believe.

You can cut a new story out of that. This Downing Street looks to have a competence problem. The EU does not need to make concessions to this administration because they are weak. Or perhaps some of the old classic narratives can be dusted down: “These Tories are out of touch.”

Johnson’s “do or die” approach to ramming an EU exit through on October 31 has also created political space for other politicians to up the aggression. If you tell everyone no holds are barred, don’t be surprised when someone goes for your throat.

Indeed, there is growing evidence that the Liberal Democrats, the Remain ultras, are doing better than is being acknowledged. Their uncompromising position is currently piling up votes in the right places to hurt the Tories.

The Supreme Court judgment may be a portent of errors to come, too.

The Queen welcomes newly elected leader of the Conservative party, Boris Johnson

Cummings has a blind spot about the law. He is a fan of impunity: when he was advising Michael Gove in 2011, a judge ruled Gove’s conduct amounted to an “abuse of power”.

Cummings assumes any argument he finds convincing will convince everyone else and is a poor judge of when a fight is lost. Hence his unusually high hit-rate for legal difficulties: he has had trouble with the Electoral Commission and Information Commissioner, in addition to these other judicial run-ins.

It is in character that ministers keep hinting that they may seek to defy the intent of the Benn Act.

The Supreme Court has spoken – but this may not be the last time they are called to keep the executive in check. Britain’s problem is not that its judges are intervening in politics. It is that its lead politician may not keep within the bounds of the law.