Now for some really tough choices. With luck, some rhetorical sleight of hand here and a modicum of Irish goodwill there, Britain will soon cross the line from divorce settlement to substantive talks with the EU27. Those who promised that the UK could simply waltz away from Brussels will find this second stage even more painful than the first.

For Theresa May’s government, nine months of divorce talks have been a humiliating and yet wholly predictable rendezvous with reality. The false promises and Rule Britannia platitudes of leading Brexiters have dissolved on contact with the facts of economic and political life. Brussels, it was said, could “whistle” for a financial settlement from London. Now the prime minister is ready to write a cheque for €50bn. It was always going to be so. When Mrs May invoked Article 50 she gave away what little bargaining leverage she once had.

Phase one of the talks, however, marks only the first collision between the Elizabethan dreamland of the Brexiters and the reality of the 21st-century world. Assuming last-minute hitches about the Irish border can be ironed out, the discussions on a framework for the future relationship will be more brutal still. Look forward to another great bonfire of delusions.

Three obvious lessons can be drawn from proceedings so far. The first is that the fundamental asymmetry has emptied of all meaning any description of the process as a balanced negotiation. This too was clear from the outset. The cost of failure is proportionately much higher for Britain than for the other side. That puts power in the hands of the EU27. Even Boris Johnson, Britain’s “go-whistle” foreign secretary, must have understood by now that Italy’s exports of prosecco to the UK are not Britain’s secret weapon.

The second lesson is that after decades of membership, politicians at Westminster have not grasped how the European enterprise works. The EU above all else is a union built on laws, with the legal acquis applied evenly across member states. Put simply, this means governments cannot opt in to, say, free movement of goods, services and capital and then opt out of open borders for labour.

When the British side calls for creativity and pragmatism in setting the parameters for a future settlement, its interlocutors turn to the rule book. None is more assiduous than German chancellor Angela Merkel in dismissing suggestions that the rules might be bent if not broken in Britain’s favour. Mrs May’s “bespoke” translates into political German as “cherry-picking”. Much as the Germans are fond of their British cousins, cherry-picking is verboten.

The third lesson highlights the illusory nature of the theoretical sovereignty so prized by the Brexiters. Britain, they promised, would regain the sovereign right to wave goodbye to the morass of regulatory agencies overseeing the acquis. This has been shown to be the sovereignty of the person shipwrecked on a desert island.

Britain can “take back control” — as long as it accepts, say, that business data-sharing will be outlawed, that British airlines will be barred from European airspace, and that electricity interconnectors with the continent will be shut down. This is just the start of the list. Anyone for sovereign self-harm?

Carry the lessons through to phase two and some conclusions can be drawn. One is about the nature of any transition agreement if and when (nothing about Brexit is certain any more) Britain formally leaves the EU. If Britain wants to benefit from access to the single market for a period after departure it will be obliged to continue to respect all the rules. This includes complying with new regulations, acknowledging the jurisdiction of the European Court of Justice and continuing to pay its full financial contribution to the Brussels budget.

Another safe deduction is that unless Mrs May relents on quitting the single market and customs union the only framework on offer for a future trade deal will be one that complies with the central principle of the acquis: the benefits are restricted to members. British talk of a Canada-plus-plus-plus deal — attaching bespoke access arrangements to the model of trade agreement negotiated by Canada — is a non-starter.

Mrs May might think she is entering a negotiation. Her interlocutors have made up their minds. A German official sums it up: “Britain decided unilaterally to leave the EU. Now it is up to us [the 27] to decide what agreement we are prepared to make with a third country.”

The Europeans are not in a hurry. They calculate the conclusion of a trade deal, as opposed to a framework accord, may anyway take five years or longer. This leaves them confused as to what Britain intends after a two-year transition. What happens during the period between the end of a transition and the operation of a new trade deal? I sense yet another retreat.

There could of course be a silver lining in all this. The roadblock presented by the Irish border is a reminder of just how hard it is going to be to reconcile the realities of Brexit with the splintered politics of Westminster. Surely there must come a point when all but the ideological die-hards begin to ask whether the game is worth the candle?

philip.stephens@ft.com

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