Over the weekend, in that murky world of news briefings, Number 10 let slip that the government intends to sanction more grammar schools. There was much subsequent rejoicing from traditionalist enclaves. “A grammar school in every town” was, after all, a much-touted slogan of Ukip.

In truth, there hasn’t yet been the same fanfare for the unspoken accompanying announcement - that, by definition, the government will also be opening more secondary moderns.

Because, as we all know, you can’t have one without the other. If some children are to gain educational access through selection tests, then others will lose access through failing them.

Thus, less than a month after Theresa May’s proclamation that she would bring social justice to a fractured nation, her lofty words of optimism evaporated with a rhetorical whimper.

Ms May was, of course, herself a product of a grammar school. Indeed, last year she supported a decision to allow Weald of Kent Grammar School in Tonbridge to open an ”annexe” in Sevenoaks.

We pause at this point. At the risk of reverting to nerdy English teacher mode, I must insist that we consider the language used to justify the Kent grammar school expansion. It’s part of the narrative.

Focus on that word “annexe”. The Oxford English Dictionary helpfully illustrates its definition with a school-based example: “A building joined to or associated with a main building, providing additional space or accommodation: the school’s one-storey wooden annexe - from Latin annectere ‘connect’, from ad ‘to’ + nectere ‘tie, fasten’.”

Given that Weald of Kent School’s new site was some 10 miles away, justifying new grammar school provision as an “annexe” is as much a semantic as it is a geographical contortion. Such linguistic somersaults provide a definite sign of the Number 10 commitment to the selective school cause.

Let us at least hope that they don’t try to vindicate their thinking on the grounds of social equality. If they do, people of varying education perspectives - teachers, school leaders, advisers past and present, academics, and even favoured gurus of the most market-forces-oriented thinktanks - will all spontaneously snort in shared disbelief.

After all, no one but the chronically sentimental or historically myopic would any longer claim that grammar schools represent a stepping stone to social liberation. They may have done once, in a different long-gone era. Now they are merely the stuff of swirling mythology.

The past, after all, is another country. The global hopes and dreams of the 21st century are different from the social reunification agenda of post-war Britain, with its need for different stratified tiers of leaders, managers and workers.

Today the evidence points the other way - that selection embeds social division. I don’t need to cite the research. Like bunting at a village fete, it hangs all about us.

The government’s grammar school decision therefore tells us all we need to know about its priorities. It’s about survival. With the enormity of the Brexit fallout to navigate, the ghost of Ukip, a fractured populace to appease, and a Commons majority of just a dozen MPs, Theresa May needs every friend she can muster.

So stuff the evidence on grammar schools. This must seem a cheap and alluring way to win a sliver of favour - from the fickle goodwill of some middle-class parents to the short-term bolstering of a hundred or so Tory MPs.

‘A Britain we thought we’d left behind’

But wait and see what the decision unleashes. Friends who live in areas where grammar schools prevail rarely talk of the quality of the actual schools. It’s the relentless hinterland of 11+ coaching - sometimes starting from the age of 5 - and the long shadow of test anxiety, and the sense of family shame if a place isn’t won.

This, for too many, is the reality of selection, and a reminder of why the middle classes fight so hard to seize their child a favoured place.

No wonder that if you want to see Britain at its most socially fractured, you need look no further than areas with grammars and secondary moderns. It’s a vision of Britain we thought we had left behind.

It’s not just the decision that’s woeful. It the timid, unprincipled nature of it. We had hoped we were beyond a narrowly ideological era when education policy was hatched by thinktank wonks who’ve never set foot in a state school, let alone taught in one. That seemed to be the hallmark of the Govean period.

These days, we were led to believe, it was all about the self-improving school system. I have listened at various conferences to former school leaders, now working for government agencies, as they pointed out the influence we - current school leaders - can wield across the education system.

Look, they said, from Ofsted to the national and regional schools commissioners to the National College for Teaching and Leadership - these are institutions with former headteachers at their helm. This is the self-improving system in action.

Quite right. But power should work both ways. Influence should be upwards as well as downwards.

After all, he who pays the piper calls the tune. We mustn’t just play along uncritically if we believe the policy is damaging.

So if the grammar school decision is as socially divisive as many of us believe, and is devoid of an evidence base to justify it, then now is the time for former school leaders in their positions of influence to make that case loudly, forensically and definitively - whether in public or behind Whitehall’s closed doors.

Their actions will demonstrate whether the self-improving system is genuinely based on trust in our professional judgement, or instead renders us the hapless enforcers of other people’s misguided policies.

Geoff Barton is headteacher of King Edward VI School, a 14-18 comprehensive school in Suffolk. He tweets as @realgeoffbarton

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