Garvan Walshe is a former National and International Security Policy Adviser to the Conservative Party and CEO of Brexit Analytica.

To arrive in Britain is to arrive in fog; but the longer you spend here the more a vague, subterranean kind of social organisation begins to assert itself, and you baffle people by not fitting into its ten thousand categories.

It’s at its most uncanny in gentrifying inner cities, where, like in those parts of “integrated” Northern Ireland or Sarajevo where the different communities lived together but everyone knew exactly who was Catholic, or Protestant, Serb or Croat, everyone knows who’s working or middle class. The parents collect their children from the sure start centre together, but their children play at different parties.

By justifying her proposals to end the ban on new grammar schools on grounds of social mobility, Theresa May walked straight into Britain’s class cold war. In this sectarian conflict of class identity she announced the Government would be changing sides. Away from the poorest of the poor, whose life chances the Cameron administration had a genuine if patrician mission to improve; and towards the group who feel most threatened by state help for the those just below them, the people “who can just about manage.”

In doing so she stirred up opponents: the patricians, swept aside by May’s thorough recasting of the government (thorough in the Wentworth sense of the word), and the guilty middle classes who can supply by means of large mortgages private tutors an an educational culture beyond the poorer people’s reach. Mere political enemies, and a new educational establishment shaped by Michael Gove, who understands the importance of a Leninist reshaping of institutions, have joined the fray too. For them, “social mobility” is measured only by how far the lowest, defined as those receiving frees school meals, are raised up, not by how widely the opportunity for a stretching education is spread.

As things stand, a Bill for selection will not get through Parliament. There are, it would seem, some 40 backbench Tory MPs set against it. And far from being a useful device to appease the right wing of the party, not a few Brexiteers can be counted among them. Since it was not in the manifesto, the Lords will feel free to block it as well.

Failure would do serious damage to the Government. Brexit is a necessity, forced upon her by the voters; a government for those who can “just about manage” is her signature, and selection in education her war of choice.

The consultation on academic selection wisely avoids setting up a singe target for opponents to aim at; but the Government needs to have a clear aim in mind. It should be to eliminate Labour’s legislative ban on grammar schools, allowing further reforms to be enacted later without more legislation.

This it can achieve if it takes advantage of by dividing the opposition. People against selection on ideological or class grounds won’t be bought off, but most Tory opponents, and even a few Labour ones, might be.

Moderate opponents need to be reassured that the Government won’t stop focusing attention to improving the “substandard” schools that still educate 1.25 million children in this country. Allowing academic selection shouldn’t be incompatible with that; after all, the Department of Education ought to be able to do more than one thing at once.

Second, the Government needs to address the brain drain arguments, of which there are two. The first, that able children bring the overall level of attainment in a school up, may be true in fact, but is monstrous, and just be rejected. Children shouldn’t be used as instruments of social policy: the education system should be run for their benefit, not the other way around. The other is more subtle: because teachers prefer grammar schools, it is feared the good ones will will leave comprehensive schools. This preys on the minds of otherwise neutral Tory MPs who happen to have good comprehensive schools in their constituencies.

Such schools need more flexibility to offer better pay and conditions to attract good staff: academy freedoms allow them to do so. Where new selective schools are opened, conversion to academies should be made easier or maybe automatic for the rest. This won’t please traditional opponents of school reform; it will rile them further; but is surely old hat to treat teachers as a unionised industrial workforce subject to collective bargaining, rather than a profession where individual performance is rewarded. And multi-academy trusts that can deploy staff across several schools should eliminate the problem entirely. Teachers employed there can teach at selective and unselective schools in the same trust.

Theresa May’s return of selection to the British education system has run into much more opposition than originally expected, but with good planning the opposition can be overcome. It need not be her poll tax: it could be the decisive defeat of antiselection ideology in British education — her miners’ strike.