Whatever else they differed on, the three intellectual traditions that built the labour movement – Marxism, anarchism and social democracy – shared a vocabulary about the dynamics of social conflict. They understood that the elite’s control of money, media and the state allows it to shape those dynamics for most of the time. They were confident that the great progressive counter-power – the working class – would self-renew, even if this would sometimes require the entire movement to relearn its ABCs.

They did not panic when they were losing because, from Peterloo to Orgreave, they were losing most of the time. They understood the concept of a reactionary period, and that you have to grit your teeth and ride it out. We could do with a few people on the left who understand that now. One of the saddest aspects of mainstream Labour’s panic about the party’s poll rating is its refusal to understand the objective causes; its refusal to debate the origins of the problem within the class dynamics of Britain; its determination to reduce everything to the issue of Jeremy Corbyn, his politics and his leadership style.

The question we need to start from is not: “Would a different leader nudge the poll ratings up 3 points?” It is: “What’s going on with capitalism, and what are the elites trying to do?”

What’s going on with capitalism is fairly clear. It is ten years into a period of stagnation, mitigated by the life-support mechanism of central bank money. Since quantitative easing (QE) fuels the asset wealth of the rich but not the incomes of the vast majority, consent for the situation is draining away. Large numbers of people – far more than those who vote for xenophobic

parties – have begun to pressure political elites in the direction of national economic solutions. That’s what the Brexit vote was.

In Britain, among the super-rich and the professional political class, there were almost no takers for economic nationalism until 2014. Then the Scottish referendum presented the glimpse of an opportunity: Labour’s addiction to unionism would severely erode its support in Scotland, making a majority Labour government impossible for a generation.

It was to double down on this opportunity that David Cameron and George Osborne tried to get Labour to front up the Remain campaign. Under any other leadership, it is likely that Labour would simply have paraded around its working-class heartlands, urging an uncritical Remain vote, destroying its credibility, as in Scotland. It is to Corbyn’s credit that he did not.

However, by losing the EU referendum, the liberal wing of Conservatism signalled that it was no longer the optimum political vehicle for maintaining consent. Conservatism, ever flexible, came up with a new one: the desiccated neo-Thatcherism of Theresa May. The “hard Brexit” faction that now controls the cabinet wants to dismantle the last vestiges of social protection for workers and the poor in Britain, together with human rights law and much of business regulation. Hard Brexit means hard Thatcherism.

However, for the next two years, its supporters need to keep as quiet as possible about the social and economic consequences. This is the source of their susceptibility to tactical pressure from the opposition – as with the amendment process forced on them over Article 50, or the National Insurance U-turn. They will give ground on the detail as long as the strategic path remains unchanged. The main task of a political opposition, then, is to thwart the strategic aim: hard Brexit on a Thatcherite programme of deregulation and destruction of public services. That is the criterion by which Labour members and supporters should judge Corbyn.

There are three parts to the task: a) pursuing the softest form of Brexit, if possible remaining in the single market; b) promoting Scotland’s right to remain attached to the single market, if necessary at the cost of independence; and c) opposing the Tory austerity and privatisation programmes on the streets, in the workplace and in the courts.

Looked at this way, Labour’s problem becomes obvious. With the right-wing media and the state pledged to hard Brexit, Labour must be prepared to become an enthusiastic party of soft Brexit, socially just Brexit, anti-racist Brexit. Yet its support base is composed of groups that find it difficult to cohere around this. Members of the urban salariat, many of whom still fantasise about a second referendum or a legal challenge, will adopt the soft Brexit strategy only reluctantly. In small-town, working-class communities, with Ukip and the Tories accusing anyone who wants to be in the single market of treason, it may not be possible to bring all former Labour voters to the project of single market access, let alone membership.

Corbyn should be judged on whether he can demonstrate the leadership skills and build the networks that can pull the separate Labour movement demographics together around the single project of soft, socially just Brexit.

The shadow cabinet has learned the hard way that fighting the new problem in the old way does not work. Brexit reframes all issues around the national economic interest – and it is likely that the hard-line negotiating position of the EU27 will do so even more. Simply campaigning against cuts, poverty, inequality and poor service provision gets you nowhere as long as those running the Daily Mail and the Sun can point their patrician fingers across the Channel (or at migrants here) and say: there’s the source of the problem.

Hard though it is, the design and execution of a Brexit strategy are doable tasks for Labour. The near-impossible one is to recalibrate its relationship to Scottish independence. Substantial numbers of the left-leaning workers, students and salariat who should be Labour north of the border have switched to the SNP, pushing it further towards social democracy. Probably the only effective gesture that Corbyn could make is to federalise the Labour Party aggressively and swiftly, in a way that allows the Westminster leadership to begin building a progressive alliance with the SNP at Westminster. Given the balance of forces within Labour, that does not look likely.

However, the third main task – opposition on the streets – is in the bloodstream of the Corbyn leadership and much of the activist base around him. While many Labour MPs found better things to do on the day of the NHS demo in March, an estimated 250,000 people took part; two weeks later – and despite calls to boycott it because of the involvement of the Socialist Workers Party – 30,000 people joined the anti-racism march, again with the participation of the Labour and TUC leaderships.

The Parliamentary Labour Party needs to stop sabotaging and undermining the leadership. It needs to accept that the balance of forces inside Labour’s broad church has moved to the pews on the left of the aisle. For those who can’t accept this, it would make everyone happier in their skins if they found a different party to be in.

The leadership needs to firm up its “red lines” in the Brexit negotiations. The detail of Keir Starmer’s “six tests” scarcely matters against the need to pledge, loudly and irreversibly, that if they are not met Labour will vote down any Brexit deal in the Commons. Labour’s support for the rights of EU migrants already in Britain has been admirable and unwavering – but now it’s time for the party to have a debate and a vote on the immigration policy that it will propose as a replacement for free movement.

If all of this were done enthusiastically, the results could be, quite quickly, a rebound in Labour’s ratings to the low thirties, the return of key Brownite politicians to frontbench politics, inroads into the SNP vote in Scotland, and far less ammunition for the hostile press and TV to fire. In turn, that would make succession planning beyond Corbyn less adversarial, with all wings of the party able to think clearly about the kind of leader a social-democratic party needs in a country that is about to self-destruct, and how the different wings of Labour could work co-operatively, instead of destructively as at present.

But the crucial period for Labour will likely be winter 2018-19. Theresa May’s Brexit strategy will fail; the EU27 will call her bluff and – if not overthrown by a coup inside the Tory party – she will lead Britain off the cliff of a “no-deal Brexit”.

In that situation, Labour has to be prepared to come to power, metaphorically, as an insurgency: assailing the Tories not just on the green benches but in the courts and by mobilising on the streets. The demands would write themselves: no Brexit without substantial access to the single market and an early election to decide the issue.

By then, large numbers of British people would understand the economic, constitutional and environmental catastrophe that Theresa May has designed for them – and my only fear is that even the radical left within Labour and the unions will not be radical enough when the time comes.

Paul Mason is the author of Why It's Kicking Off Everywhere