And so it begins. The withdrawal letter has been delivered. The trigger has been pulled. The obligatory presidential tweet has been sent. Article 50 is engaged.

Today’s political and media attention is, unsurprisingly, focused on the next stages in the Article 50 process. The European Council President Donald Tusk has already announced that he will convene a meeting of the European Council – meeting as the EU27 – on 29 April to determine the guidelines that will shape the negotiations. In light of these guidelines, the General Affairs Council is scheduled to meet on 16 May and it will establish the negotiating mandate to be given to Michel Barnier and his team of European Commission negotiators. As early as next week, the European Parliament will consider a draft resolution setting out its key demands for the negotiations.

It’s all very structured. There are dates and timeframes. Institutions have their roles. There is a process set down in law. It is orderly and constitutional. This is what the UK is engaging with. This is what the UK is leaving behind.

Meanwhile, the UK is a constitutional mess.

The UK Parliament legislated for a referendum without giving the government the legal authority by which it could act on a vote for the UK to leave the EU. The UK Supreme Court insisted that the UK government obtain legislative authorisation to trigger Article 50 rather than using prerogative powers. And so it made Parliament complicit in Brexit rather than leaving responsibility with the government.

Parliament duly went through the motions, failing to clothe this naked Brexit with any amendments that might have shaped either the process or substance of Brexit. Having demanded that the Executive act accordingly to law, the Supreme Court passed the buck to an Executive that controls the Commons, unimpeded by a bloated and impotent unelected Lords. If the fabric of the Palace of Westminster is overdue a renovation, it is nothing compared to the fragility and frailty of the democracy it contains.

The UK’s withdrawal from the EU is being steered by a Prime Minister that has not faced a general election as leader and who has shredded her party’s manifesto commitment to keep the UK in the Single Market.

Power-sharing in Northern Ireland is stalled with the possibility of direct rule hanging over it. Brexit has destabilised Northern Ireland with some seeing this as an opportunity to make its inhabitants choose between a united Ireland inside the EU or a United Kingdom outside of the EU.

Following its symbolic motion to reject the triggering of Article 50, the Scottish Parliament has now voted in favour of seeking permission to hold another independence referendum on the pretext that the UK’s withdrawal from the EU constitutes a material change since the 2014 referendum.

One divisive referendum begets another and another while our parliamentary democracy observes the chaos with utter bewilderment. What must our European neighbours think of us?

We have no process to manage this chaos. We have no structures and institutions to manage the domestic repercussions of Brexit.

And if the complaint about the EU is that it is overly-constitutionalised, then the complaint about the UK is not just that it is under-constitutionalised, it is apparently de-constitutionalising.

As the UK moves to end a membership of a European Union that voters felt was no longer in the UK’s interests, it has to confront its own political union, and a growing sense among many of its its members that this union and its values feel increasingly constitutionally inauthentic.