IT was the week when we were meant to glimpse the Global Britain of the future. Just think, only a year from now we will have exited the EU. The panjandrums of the Commonwealth gathered in London in a multicoloured demonstration of how many lost historical trading threads we might pick up again.

High summer came early (at least in England), and the Queen celebrated her 92nd birthday, with Ed Balls serenading her on the ukulele in the Albert Hall. What more did we need to persuade us that the future is bright and that Global Britain, as in days of old, will be a commercial empire on which the sun never sets!

Except it has not turned out like that. Prime Minister Theresa May in particular is one in whose mouth a sour taste will linger for a while yet. Her prowess in everything that requires a little grace or finesse or emotional intelligence proved lamentable once again. Always avoiding anybody unlikely to say what she wants them to say, she at first refused even to meet the Caribbean leaders just arriving in London as the dimensions of the Windrush scandal emerged.

Wiser counsels soon prevailed even in Downing Street, but her promise of compensation “where necessary” could not hold back the flood of heart-breaking testimony from immigrants who had been persecuted or even deported on orders from the Home Office she once ran. She lost control of events in a way that may well bring more political retribution in the months to come, not least from ministers needing to carry the can for her past blunders.

And yet those Commonwealth leaders that May turned off were the very ones she also intended to woo for new trade deals ready to slot into place after Brexit. Can we really talk of Global Britain in the same breath as the “hostile environment” to migrants which she has fomented?

The globalisation of recent decades is not a seamless garment, but liberty of one kind tends to encourage liberty of another. Trade, indeed international contact of every sort, is certainly now more open than at any time since a world war brought the first great age of classical economics to an end in 1914. Aspiration to restore a modern version of it lies in the EU’s concept of the “four freedoms”, meaning freedom of movement for goods and services, for capital and labour. Since the beginning of Brexit, the EU has insisted these freedoms are indivisible: you cannot curb one while keeping the others.

It is true this aspiration has now come under bloody-minded challenge from Donald Trump. We can only look on appalled as he seeks to wreck the renewed progress towards economic liberty, though so far his success has been quite limited. Theresa May offers but a feeble imitation. He at least has the virtue of a horrible consistency, so that you know where you stand with him. She suffers from a pathological lack of candour, so that she is all over the place.

For her one definition of Global Britain is a country where foreign workers, however useful, will find it harder to get in, or to come and go. British industries and companies already say this will damage them, yet she stops her ears. Why should any other countries, not least the members of the Commonwealth, offer her in return the special deals which she claims will solve all our future trading problems?

The tensions are not going to go away. Last week, as the the House of Lords worked through the Brexit bill, it inflicted a heavy defeat on the government when it voted to keep the UK inside a customs union with the EU. In other words, all the existing 28 members would continue to trade freely among themselves while maintaining a regime of common external tariffs against imports from outside. This week, the House of Commons will hold a vote on the same issue, a non-binding vote but one that allows Tory Remainers to team up with the opposition parties. It could set a precedent for when the bill returns to the Commons in the summer and takes its final shape.

All this has made the customs union question a dangerously weak spot in the government’s defences of its bill, because of Northern Ireland. If there is no customs union between UK and EU, then there has to be a border, more or less hard, across the island of Ireland from Newry to Derry.

It is an appalling idea as a potential incitement to terrorism, and the government in Dublin would in any case never accept a Brexit deal which entailed it.

The UK argues that various non-physical controls could serve instead but last week the word came from Brussels, in no uncertain terms, that these weird and wonderful schemes had been dismissed as unworkable. That is to say, the only way to save the situation in Northern Ireland would be for the UK to stay in the customs union.

This was no doubt why, after the Prime Minister returned from a weekend at Chequers, we read in the newspapers, courtesy of her spin-doctors, that her resolve to leave the customs union remained perversely undiminished. In the face of a vote she would be likely to lose, she could hardly say anything else.

But the whole history of Brexit is one of her government getting itself into positions which are inherently unsustainable and then, after much huffing and puffing, abandoning them. It is a mark of weak leadership.

We can see it coming once again. In those same newspapers, we might also have read how May’s inner circle had “war-gamed” the results in case of a decision to stay in the customs union after all.

They boiled down to the resignation from the government of Boris Johnson and Liam Fox. Few tears would be shed outside the Tory party, though no doubt there would be a crisis inside it: revolt of the right wing, possible leadership challenge, perhaps an early General Election.

Even without anything so dramatic, the troubles would not be over. For after the question of the customs union comes the question of the single market – the internal project for members of the EU to dismantle barriers so they can trade as freely as possible with one another. Again, practical progress has often been sluggish, but all the same it has taken place.

The UK has pushed it forward because the single market was the UK’s own idea, originally owed to Margaret Thatcher, no less. Why on earth May’s government has been so insistent on leaving it is a mystery. After the customs union, it could be the next abandoned sticking point. At that point Brexit becomes scarcely worth the candle.

Who knows where we will all be a year from now. Yet for the first time we can perhaps perceive a glimmer of hope that Brexit will in fact never take place.

The matter is not entirely in the hands of a wounded and limping UK Government. In the public at large, a feeling stirs that there should be a second referendum on the eventual deal. The EU thinks it useful to assure us we could still change our minds.

There would be a price – curtains for May, a Tory split – but there’s nothing on the horizon looking remotely as expensive as Brexit.