If Jeremy Corbyn wants to provide real leadership on Brexit, he should come out for the single market

Well, there you have it. Jeremy Corbyn has confirmed that Labour would seek to keep the UK in a customs union with the European Union post-Brexit. The move was expected; still it is worth unpacking just what it means.

The first point is that the economics is sound. Brexit is largely an exercise in damage-limitation: the closer Britain remains to its largest trading partner, the better. While membership of a customs union would restrict Britain from striking its own free trade deals, this is more than offset by the advantages of closer partnership with Europe.

The politics is for the most part sound also. The Labour Party has struck a balancing act on Brexit so far: its tactic has been to triangulate, committing hard to neither the Remain nor Leave cause in order not to isolate its young metropolitan voters nor its working class heartlands. But the party has tried to keep a step further towards “Remain” than the Tories at each stage in the process. This move ensures that it keeps doing that—without isolating either camp through full policy clarity.

But there was one important thing missing from this announcement.

Much discussion of Brexit over recent weeks has focussed on the intractable problem of the Irish border. The argument has been that a full exit will entail the erection of a hard border because, thanks to one system in the North and another in the Republic, checks will be required when goods are transported over the line. That this would present problems for the Good Friday Agreement struck 20 years ago is obvious.

Corbyn’s speech goes some way to assuaging this concern. He has not come out in favour of membership of “the” EU customs union, but is signalling that Labour is open to recreating a similar system, with a common tariff on outside goods coming in.

“A customs union is a necessary step in the right direction," says Sam Lowe, an analyst at the Centre for European Reform think tank. The problem is that it is only one part of the puzzle. "It only gets you so far," Lowe confirmed. It cannot itself prevent a hard border.

The reason for this is that tariffs are not the only thing necessitating border checks. "The customs union does not include any provisions for overcoming regulatory barriers” Aarti Shankar, a policy analyst at Open Europe, told me. Yet these present just as great a problem for preserving the open frontier.

What to do? Lowe explained: “On top of being in a customs union, the UK (or just Northern Ireland) would need to remain in the single market for goods and probably the EU VAT area also.”

The odd thing is that the signs are Corbyn knows all this. Indeed, in his speech he used ambiguous phrasing when he argued that the new policy would “help avoid any need for a hard border in Northern Ireland” (my italics.) Yet on the single market there was only boilerplate waffle about “maintaining the benefits” of membership.

The Labour Party is currently making the running on Brexit. Its new customs union stance commands wide parliamentary support—so wide that the government is likely to be defeated on key Brexit legislation if it maintains its current commitment to CU withdrawal.

Now would be a good time for Corbyn to take that final step and come out for single market membership. He ruled out this course of action today and in no uncertain terms. But when the political wind changes, so do the policies. Corbyn is slowly demonstrating that he is no exception to this rule. Watch this space.