Putting together our newslinks on Thursday morning, there was a clear theme to the coverage of the previous day’s events: it was “an attack on democracy” that has, as Jonathan Freedland eloquently argued in the Guardian, given people a new perspective what often seems a remote little world of its own.

Writing in CapX meanwhile, Alex Massie explains well why targeting Westminster made Wednesday’s terrorist attack more symbolically potent than an equally lethal but more random assault on a shopping centre or high street:

“Democracy is more than a building, naturally, but the building still matters as a statement of a shared commitment to the principles we have decided, over the years, decades, and centuries, should define us and shape the way we conduct our public affairs. Institutions, so often questioned in an age less deferential than its predecessors, still matter.”

Given the constitutional turbulence we can expect for the next few years, it would be a precious silver lining if this week’s events help to rehabilitate Westminster.

The seat of our common Parliament has been out of fashion for a while in the sort of circles that like to discuss the constitution. This sentiment encompasses both the building – a national and indeed international symbol of democracy, but so old-fashioned – and the work that goes on inside it. As a result is has leaked power and authority to in all directions: to the courts, to Brussels, and to the devolved legislatures.

Brexit offers an opportunity to revive its fortunes – Andrew Marr has set out the exciting possibilities – but it can’t simply be assumed that the political will is there to seize it.

A chronic unwillingness, or inability, on the part of our political class to defend the common British decision-making which Westminster represents has seriously undermined the effort to keep this country together. No separatist challenge can be met except with promises of “more powers!” – that is to say, of less Britain.

Unsurprisingly this strategy, hinging as it does on rejecting the Nationalists’ conclusions whilst accepting most of their premises with regard to the value of British governance, hasn’t worked and shows no sign of working. Yet it continues unabated.

For example Carwyn Jones, the First Minister of Wales, harbours such distaste for British government that he’d rather create a complex and expensive system of ministerial councils and courts than simply have powers exercised from London that he is quite content to be exercised from Brussels. Gordon Brown wants Scotland to be granted the right to sign its own international treaties, which isn’t a feature of any actual federation on earth – just ask Bavaria or Texas.

This anti-Westminster ‘federalism’ is so dangerous because it fails to replicate the countervailing forces which hold other federations together. British federalists offer no route to a common identity as strong and cohesive as Germany’s, no grand idea such as that which underpins (at least until recently) the United States.

Britain and Britishness grew up around institutions such the monarchy, the Armed Forces, and the (now not-so-National) Health Service. Our common Parliament and parties are a key part of what creates and sustains the British community, and make it a concrete and consequential one rather than a mere collection of sentiments or imagery. Diminish them and that sense of Britishness dwindles too.

Many wise heads have written, in the aftermath of 2014’s independence referendum, that unionists need a more persuasive emotional case for the Union if it is to survive a change in Scotland’s economic fortunes. But relatively few have noted how incompatible is that need with the ongoing disavowal of our common institutions, and Westminster most of all.

If Theresa May wants to spare the UK from either the quick death offered by Sturgeon or the slow one offered by Jones then she must work out how to sell ‘Westminster’, which amongst other things is shorthand for making decisions together as Britons. Defending the legitimacy of the Brexit decision – which she has done with gusto – ought to give her a head start.

Parliament is what allows Britain to be a vehicle for the ‘pooling and sharing’ of wisdom as well as cash. It’s record at least stands up to those of the devolved legislatures, which have proven rather sentimentally and ideologically narrow places.

If unionists can’t be enthusiastic about it it’s hard to see why sceptical swing voters would be convinced of Britain’s merits.

Whatever you think of Brexit, it offers a real opportunity to breath new life into Parliament, and thus into our common politics and the identity and country it sustains. The Government must take care to seize it.