THE so-called British Constitution is like a shapeshifting invisible black cat that stood in a tray of fluorescent paint. You cannot see the cat. Its presence can be heard and felt, but never really observed. You can, however, see its footprints.

And it is a well-travelled cat. From Canada’s icy wastes to Australia’s burning deserts, from the tropical shores of the Caribbean and the South Pacific to the steaming jungles of India and Malaysia, you can see the imprinted legacy of the British constitution, like the stamp of cat’s paws, clearly written on the page of written constitutions everywhere.

Only in the UK itself, by some strange quirk of absurdist constitutional metaphysics, does the cat’s paw not leave any trace. If we want to know what the cat looks like – what shape it shifts into when on home soil – we have to look at those prints elsewhere and reconstruct them, like a cryptozoologist guessing the Yeti’s height from a dent in the snow.

So, here’s this week’s question about the cat. Does the shapeshifting invisible black cat allow a prime minister to advise the Queen to prorogue parliament (that is, end its session and send all the MPs home) in order to avoid a vote of no confidence, and, if so, is the Queen required by convention to act in accordance with that advice, or does she have some discretionary power to refuse prorogation?

The answer (because we who study shapeshifting invisible black cats are very clear on these things) is “absolutely not and of course”; or, if you prefer a more finely balanced answer, “almost certainly and probably not”.

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The reason is that prorogation is primarily governed by convention: that is, by the unwritten rules of acceptable political behaviour worked out by gentlemen – usually by private letters between the prime minister and Queen Victoria’s personal secretary – in the 19th century, or by letters to The Times in the 20th century.

These conventions are not authoritatively written down in law, although the Cabinet Manual is the closest we have as guide to their content.

This states that “Prorogation brings a Parliamentary session to an end. It is the Sovereign who prorogues Parliament on the advice of his or her ministers.”

So, there you have it. The Queen prorogues on the advice of ministers; there’s no hint there of any discretion to refuse that advice. If the Boris wants to do a Charles I and send Parliament packing, he can.

And indeed, that is what we find when we examine the paw-prints. The constitution of Barbados says, “The Governor-General, acting in accordance with the advice of the Prime Minister, may at any time by proclamation prorogue Parliament.”

That of Jamaica says, “The Governor-General may at any time by Proclamation published in the Gazette prorogue […] Parliament” and that “In the exercise of his powers under this section the Governor-General shall act in accordance with the advice of the Prime Minister.”

Only, perhaps it’s not quite as simple as all that. By convention, the prime minister’s authority to advise the Queen stems only from the confidence of the House of Commons.

If the prime minister does not possess such confidence, then he is not a responsible adviser, and it becomes the Queen’s duty either to find another prime minister who can command the confidence of the House, or else to dissolve parliament.

The Fixed Term Parliament Act muddies the waters.

It regulates one side of this equation (dissolution) but not the other side (the appointment, the resignation and removal of the prime minister).

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It is not clear, in this context, how the conventions should apply, if at all. We are still left in a quandary as to whether it would be “constitutional” for the Queen to refuse or delay prorogation.

The related but not identical question of whether it would be proper for the prime minister to request prorogation in such circumstances is also unanswered. The constitutional cat slinks into the gloom.

But these are not, ultimately, the interesting or relevant questions.

Instead we should be asking why the rules are so shadowy and invisible in the first place.

Shouldn’t the basic rules by which we run a country be clearly set out in a supreme law, for all to see?

Secondly, we should be asking whether this is, in principle and in practice, a good rule. Regardless of whether or not he can, should the prime minister have a power to prorogue parliament at will?

Is it right for a prime minister to have such a power? If so, what constraints should be placed on its use?

Thirdly, we should ask by what authority these rules exist? Who made them? How can we change them?

A proper written constitution, approved by an inclusive process, could bring it into the light and set it right.

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