If the United Kingdom is ever to operate her foreign and military policy with consistency, celerity and decision, then some brave Prime Minister is going to have to bury our newborn convention of asking Parliament’s permission at every turn.

The right to declare war is a Royal Prerogative. Technically it rests with the Crown, which is basically a constitutional gun room in which the Government stores powers which might see excessive use if left in the idle hands of some ambitious, full-time functionary, like a President.

David Cameron and his successors do not, in this instance, appear to legally need a Commons vote to unlock this box. That they act as if they do is one of the many miserable legacy’s of Tony Blair’s epic mishandling of the Iraq War, and it is crippling British strategic planning.

Who in their right mind, after all, would make high-information, high-risk, time-sensitive decisions contingent on the consent of a committee of 650 people?

Whether or not you think strategic bombing works – and there’s a good case to argue that they don’t – the idea that it should work in Iraq but not in Syria is nonsense.

At present, the RAF pummels ISIS in the one country, only for the army of clerical fascists to limp back over an arbitrary line in the desert and be safe, free to regroup and resupply.

Readers might recognise such strange rules of engagement from playground games of tag. They are not ordinarily a feature of grown-up warfare.

Writing in the Daily Telegraph, David Blair sets out the problem in detail. MPs are not judiciously and sombrely concluding that there is no case for action: they are carefully constructing rules by which the case for action will never be met.

Instead, the Prime Minister is urged to work for peace. As if the thought hadn’t occurred to him.

Of course, the best part of being a “peace facilitator” is that the role involves no risk, and if we fail the fault lies with the sadly un-enlightened powers we were brokering with.

As the civil servant put it in Yes, Prime Minister, we shall offer our interests and allies in the region “every support, short of help.”

The great strength of a fluid constitution like ours is that it allows new conventions to evolve organically, in response to circumstances.

But any growing thing needs a trim from time to time, and the Government must retake the power to make the big calls, especially operational decisions in campaigns we are already waging.

Otherwise we will continue to embolden our enemies, and diminish in the eyes of our allies.