There are several significant angles to last night's Commons vote on Syria. Foreign policy experts look at Britain’s role in the world and our relationship with the United States; domestic politicos look through the prism of party politics, asking who came out better between Miliband and Cameron. Meanwhile, Syria continues to suffer and we can only now hope that inaction is the lesser of two evils.
But amid the fallout, easily obscured by the more obvious issues of the day, is a seismic shift in the British constitution, an evolution that has crept up quietly but which serves to empower Parliament and constrain the executive.
While the Prime Minister officially retains the Royal Prerogative to declare war, it is clear that this power is now tempered by the convention that Parliament must vote on the matter beforehand.
Previous votes on Iraq and Libya, while contentious, saw the government of the day validated by the Commons. Before this it had been understood that the executive had a right and duty to declare war as it saw fit. The real test of this innovation was whether a government convinced of the need for military action would respect a vote that opposed it.
The fact that Cameron had to promise the House that it would have a second vote, the fact he has now changed course so dramatically – while retaining the right to declare war - shows that votes like this are not simply rubber stamps but have become a binding convention that can change the foreign policy of a government.
Ironically, by calling an unprecedented vote on Iraq, Tony Blair, the most presidential of prime ministers, set in place an innovation that created a precedent largely devolving 'war powers' from the executive to the legislature.
Frustrating for many, our uncodified constitution is nevertheless pragmatic and far from conventions being ignored (as many fear has increasingly happened) a new one that curtails government power has clearly entrenched itself.
In the Lords, former generals, admirals, defence secretaries and ambassadors urged caution, while the debate in the Commons was marked by many MPs speaking of their constituents’ concerns. Some cheap politicking (from both benches) aside, the standard of debate was high and the tone respectful.
Whether one agrees with the outcome or not, the vote was a reassertion of Parliamentary sovereignty – a message to the executive, but also to the United States, that in the United Kingdom it is with Parliament, not the Prime Minister, that ultimate power resides. Indeed, many MPs spoke of this as a retreat from British presidentialism and a return to the PM being primus inter pares.
It is now unthinkable that Cameron would disregard Parliament’s wishes. Likewise, his deference to the Commons and his claim to have listened further entrenches the precedent that any future Prime Minister would have to call a similar vote on military action.
In my view, reserve powers of Royal Prerogative should remain with the Executive in case a Prime Minster must act immediately before explaining himself or herself to the House. But it is now clear that any premeditated military action will rightly require the approval of Parliament.
The British constitution is something that has grown organically over the last thousand years. It has survived because it has evolved; its imperfections have been mitigated by its flexibility. This latest stage in its evolution has something to say of our present and of our past. It speaks to a country disillusioned with foreign interventions, war-weary and cautious of unknown consequences. But fundamentally it also reasserts an ancient British principle: Parliament is sovereign.
James Hallwood is associate director of The Constitution Society @jhallwood