Another week, another official boost to England’s increasingly embattled selective schools. The latest salvo comes from schools minister Nick Gibb, who has weighed into the growing controversy about grammar schools by suggesting that they should form multi-academy trusts with non-selective schools, to develop the right “ethos” and help to “raise standards”.

It’s hard to know where to start with this latest piece of illogicality, so let’s briefly go back to basics – a favoured government theme, after all. We know that grammar schools select the highest achieving children aged 11 and the fact that most of their pupils come out with good GCSEs is less due to some mysterious “ethos” or exceptional commitment to “high standards” than to a highly favourable intake, working in highly favourable circumstances, including a more highly qualified and stable teaching force.

We also know that dividing children at 11 suppresses both the esteem and achievement of those rejected, and makes for a much tougher job for teachers and leaders in secondary moderns (and please let’s call them by their real name and not describe them, inaccurately, as comprehensives or, worse still, “bog-standard” comprehensives). As the OECD makes clear: selective systems increase educational inequality.

Grammar Schools: Who Will Get in? – the three-part series which has just finished on BBC Two – revealed the painful consequences of the grammar/secondary modern split in the still-selective borough of Bexley, south-east London. The first programme revealed, with heartbreaking clarity, how children from poorer backgrounds are rejected by an exam that clearly benefits those from already educated backgrounds, or where parents can pay thousands in private tuition.

The second and third programmes put the spotlight on how hard the local secondary modern works to encourage and educate its pupils despite severe shortages of teachers in key subjects, while the grammar school prides, and occasionally preens, itself on its exclusive pool of talent.

But the series ended on a discordant note, with Desmond Deehan, the head of Townley grammar school, describing his plan, called Odyssey, to form a MAT with Erith school, the secondary modern, so that the latter could learn from the ethos and atmosphere of this selective school: an example that Gibb has picked up on.

Reaction has been swift, with Geoff Barton, general secretary of the Association of School and College Leaders, probably best expressing the views of most educational experts with his pithy comment that the idea was “patronising to other schools and not based on any evidence”.

Perhaps less obvious to the casual observer is how Gibb’s MAT idea is a reflection of a new defensiveness among the supporters of selective education. Since announcing her plan to expand grammar schools, the prime minister has had to face a educational establishment, and large parts of her party, that no longer believe in a divided system, not to mention the rising volumes of evidence that selection does nothing to boost social mobility or improve standards overall.

The extent of rational opposition to selection has put the government in a bit of a spin. The £50m currently on offer (over 2018-19) for grammar school expansion comes with allegedly tough strings attached: selective schools must show “ambitious and deliverable” plans to expand their quota of disadvantaged pupils over the current 3% mark. It is doubtful, however, how many will deliver on this new metric.

Gibb’s MAT proposal is, I suspect, a further smokescreen to throw us off the scent of this poorly executed plan and give embarrassed ministers (and grammar school heads) something to mutter about in front of the cameras. Certainly, it is unlikely to alter the core of injustice and inefficiency at the heart of selective education, just as the proposals, a few years back, that private schools sponsor troubled academies largely ran into the ground.

Hopefully, the public, and certainly the educational world, will see it for the empty plan it is and continue to oppose the expansion of schools that are built on rejecting the vast majority of our children. The only true odyssey that politicians of right and left need to embark upon should involve the phasing out of selective schools altogether and the creation of a unified state system that works for everyone.

• Melissa Benn is a founder of the Local Schools Network, and chair of Comprehensive Future