The signatories of a recent letter to Theresa May must have daunted even that sceptic of the business lobby. The CBI, the Institute of Directors, the British Chambers of Commerce, the Small Business Federation and the EFF, the manufacturers’ organisation, want the UK prime minister to “get on” with the enlargement of Heathrow airport.

A vote had been planned before parliament’s summer recess in July. If the deadline passes, the dread is a political class too lost in the next stage of Brexit to address the footling matter of national (in Heathrow’s case, global) infrastructure.

Notice what the employers fear is trickling away here: not support for their cause, but the time and space for it. May wants an expanded Heathrow. The Conservatives made it a manifesto pledge last year. The parliamentary votes can, with effort, be assembled. What troubles business is Brexit’s potential to crowd out the project, as it does so much else.

The parable of Heathrow illuminates Britain’s predicament since 2016. History might come to record the real cost of Brexit as all the other things not done. A generation of MPs, civil servants and public intellectuals are engaged with one open-ended mission. It is where they must spend their energies and political capital.

People who entered public service to reform the economy or see the National Health Service through the costly dotage of the baby boomers will lose vital years to the dry work of unmooring from the EU and recreating the best bits of it. Even if the direct cost of exit turns out to be as exaggerated as Leavers suggest, the opportunity cost is, if anything, underplayed.

A sense of those forgone opportunities is free to read online. In Square Deal, the Conservative MP Nick Boles has written a programme for national renewal that touches on healthcare, housing and employment. His muse is the US presidency of Theodore Roosevelt, who neutered the appeal of America’s early 20th-century populists with his own blend of active government, popular capitalism and assertiveness abroad. There is in Square Deal the filling, not just the outlines, of an electable form of Toryism.

Picking of battles

The difference is that Roosevelt’s federal government was not occupied with a huge constitutional project. Reformers closer to home, namely the prime ministers Clement Attlee (after 1945) and Margaret Thatcher (in the 1980s), had the same good fortune to govern while the basic rules of state did not constitute a distraction. The next prime minister who will be able to do the same is probably not in parliament yet.

It is possible that the “next election will not be defined by Brexit”, as Boles predicts, but the business of state still might be. Twelve years passed between Britain’s first application to join the European project in 1961 and its ultimate accession in 1973. It would be no shock if, in 2028, 12 years after the vote to leave, Britain were still negotiating features of its relationship with an EU that is itself in flux.

The political, diplomatic, technical and intellectual work that goes into the management of this bilateral tie will allow for few other undertakings of real weight. And even this does not budget for the emotional rawness of an electorate that is divided on the matter. Would the nation tolerate another round of divisive change on, say, housing?

Leavers will contest this neat line between constitutional change and the “real” work of government. They see the EU’s curbs on a member state’s freedom of action as the true block on domestic reform. A bold government must be sovereign in the first place. But even leaving aside the obvious rejoinder (which Thatcherite idea was stymied by Brussels?), there are only so many hours in a day and only so many high-risk ventures the public will bear in one phase of history. Central to politics is the picking of battles, and Britain has picked an all-absorbing one.

It is a lapse into mawkishness to say that the best minds of their generation are being wasted on a fool’s errand. The best minds are not in parliament, Whitehall or the commentariat. Nor can anyone be certain that Brexit will look foolish in a decade’s time. What is going to waste is what the modern argot obliges us to call “bandwidth”.

Britain has not the time or energy for much besides Brexit. It volunteered for a new challenge before fixing such old ones as productivity and infrastructure. If a third runway at Heathrow is to be a good idea postponed, it will not be the only one.

These are the Lost Years. We can but guess how many of them there will be, and what we might have done with them instead. – Copyright The Financial Times Limited 2018