What was Chuka Umunna’s quelled backbench rebellion all about? It wasn’t, certainly, about a principled position on single market membership, as he suggested in these pages. He had previously argued that Britain should be prepared to leave the single market in order to have a populist crackdown on immigration.

But like many on the Labour Right, Umunna is skewered between conflicting opportunisms. It is traditional for them to triangulate to the right on immigration, but they also see Brexit as a potential wedge issue for weakening Jeremy Corbyn’s leadership. This is particularly important after general election results which greatly strengthened Corbyn, blocking the accession of a fresh-faced Blairite leadership for the foreseeable future. In the words of Malcolm Tucker: unforeseeable, that’s what you are.

So, Umunna’s amendment, seeking to commit this government—and thereby a future Labour government—to single market membership, could plausibly be read as a leadership wheeze. Yet relatively few MPs were willing to get on board. Labour Remainers, according to the editor of BBC Newsnight, have expressed impatience with Umunna’s “vanity amendment.” The Remainer leader of Unison, Dave Prentis, has issued a statement denouncing this “distracting” “symbolic rebellion.”

Some have remarked on the supposed irony of Corbyn sacking shadow ministers for breaking the whip, when he is a lifelong Labour rebel. Stephen Daisley regrets that Blair never ‘sacked’ Corbyn for his rebellions. But ‘sacked’ from what? From the back benches, Corbyn was able to oppose the leadership’s line without the responsibilities and loyalties that he ought to now demand of his shadow cabinet.

Still, many decent Labour MPs with a good track record also supported the amendment. For some of them, it’s an issue of principle. But it shouldn’t be. Committing the UK to single market membership in advance of negotiations is a bad idea in principle, and not just because it was orchestrated by a conniving careerist.

Part of the problem with any discussion of the EU is that it is obscured by journalistic clichés. We talk about ‘hard Brexit’ and ‘soft Brexit.’ This sort of language makes sense in a defensive context, when ‘hard Brexit’ means “what the Tories plan” and ‘soft Brexit’ means “damage limitation.”

But if we’re really looking forward to the possibility of a Labour government negotiating Brexit, it’s time for Labour MPs, Labour-supporting pundits, and the left in general to start talking specifics.

What do we actually want out of Brexit negotiations? What are our red lines? For many on the Left, ‘soft Brexit’ has been about defending Schengenian ‘free movement.’ Indeed, it is deeply problematic that Labour conceded the argument about free movement, and is contemplating a green card system. That will not end exploitation as some think; it will create more ‘illegal’ migrants as their visas run out, driving them into the shadows of the economy and society. That benefits only the poverty employers and black marketeers—not workers.

Others are more concerned about Britain having tariff-free access to European markets—and Corbyn agrees. One can see why. Close to half of British trade is with Europe. With tariffs, any prospective Labour government would face lost economic growth, job losses, and a drop tax revenues which would render it unable to fund its spending commitments.

Then, there are such matters as human rights law, and the exiguous social, labour and environmental protections linked to EU membership. Labour has committed to keeping these protections—indeed, its commitments on workers’ rights go much further than anything the EU supports.

Given these aims, there are a few options. Single market membership would cover it. But it comes with the disadvantage of being bound by single market rules and European Court of Justice jurisdiction. This is a problem if you’re a left-wing government, because these rules favour markets and competition.

“Lexiters” have overstated this by claiming it makes nationalisation impossible; it doesn’t. But they are right to point out that the rules, and the way they have been interpreted by the European Court of Justice, are geared against state monopolies. If Labour can avoid being bound by those rules, without losing trade access, it probably should.

There is also the so-called ‘Swiss Option’ which involves membership of the European Free Trade Area and bilateral trade agreements, freedom of movement, and tariff-free access, but not single market rules. Other options begin to involve tariffs. For example, simple EFTA membership would allow free trade in goods, but not in services.

Finally, the WTO Option, the “no deal is better than a bad deal” option floated by Theresa May, would involve losing any tariff-free access whatsoever—presumably in the interests of tougher border controls.

Any settlement realistically depends on how EU leaders see the future of Europe, and what they are prepared to put on the table. For Labour to commit to a definite outcome in advance of this process would be foolish.

If Labour gets the chance to negotiate, it should go in with its red lines and its negotiables, see what it can get, and present it to parliament. Binding Corbyn’s hands in advance, simply because you oppose his leadership, is not helpful.