In 10 Downing Street, Theresa May’s team is busily at work on a strategy for Britain’s departure from the EU. First, they must establish a negotiating position for the Brexit talks that lie ahead with the other 27 member states.

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The Government’s position on the forthcoming talks is that it will provide “no running commentary”. In his television interviews on Sunday, Boris Johnson mapped out four areas of prospective negotiation: freedom of movement; the money Britain would get back from Brussels; legal liberation from European jurisdiction; and fresh opportunities for free trade agreements with other nations. That, the Foreign Secretary implied, was plenty to be getting on with.

This, to say the least, is not a view widely shared in the Commons. For Remainers and Brexiteers alike, the basis upon which the PM will approach the all-important negotiations is still frustratingly opaque. That, her allies object, is the point: a poker player does not reveal her hand in advance. But this argument has achieved little traction among MPs, who insist upon their inalienable right to preview and assess May’s basic battle-plan.

The pressure for parliamentary oversight, it is true, has mainly been applied by those who are horrified by Brexit and regard the referendum result as a ghastly triumph of populism over Britain’s best interests. What gives the Tory whips sleepless nights is the possibility that a handful of Conservative Remainers will join the other parties in defying May over Article 50. Remember: since Zac Goldsmith's defeat in the Richmond Park by-election, the Government has a working majority of only 13.

This is the short-term threat to the PM, and one that dominated much of the last six months in Westminster. But the greater crisis looming is the inevitable disappointment that many Brexiteers will feel once the talks are underway and Article 50 is invoked this Wednesday.

The referendum in June presented a “light-switch” decision: on or off, in or out. It was entirely binary, as was the campaign that preceded it. The voters were encouraged to pick the lesser of two apocalypses.

In practice, of course, our departure from the EU will be a fantastically complex and nuanced process, piecemeal and gradual rather than climactic and electrifying. For four decades, this country’s governance has been intimately enmeshed with the Brussels machine. Disentangling that relationship will take years, perhaps decades.

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Worse for those who favour a “hard Brexit” – an unambiguous, absolute break – is the dawning realisation among senior ministers that this outcome is far from desirable if Britain is to remain prosperous. As we now know, from an adviser’s notes snapped in Downing Street, they would prefer to “have [their] cake and eat it”.

Around six months after the referendum, there were signs of compromise that were interpreted by hardline Eurosceptics as a Brexit “climbdown”. David Davis, the Secretary of State for Exiting the European Union, was a powerful advocate for the Leave cause and is no pushover in negotiations of any kind. But already he is floating the idea that the UK may retain a formal relationship with the EU in return for continued payments to Brussels.

This notion of associate membership is anathema to those who believe that exit does not mean lingering at the door. At the same time, they face disappointment over immigration – the touchstone issue for most who voted Leave.

Yes, ministers say, Britain will regain control of its borders. But migration, it is already clear, will continue in key economic sectors to foster growth and preserve the nation’s economic status. Those who had envisaged the pulling-up of the drawbridge are in for a grave disappointment.

All hardliners, of whatever stamp, are inclined to see treachery everywhere. It is in their nature to detect betrayal in the operations of government, to rage as their principles are diluted before their very eyes.

The only certainty in this turbulent process is that those who argued most passionately for Brexit will be dissatisfied with the eventual deal – however good it is. This is axiomatic. It is also, against stiff competition, the most serious political danger confronting Theresa May.

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