If Theresa May wants to create more grammar schools then she must also want to create more secondary modern schools: you can't have one without the other.
Do not be fooled by the smoke and mirrors the government is attempting to create around this dangerous policy. Justine Greening tries to sell it as a way of increasing poor children’s social mobility by giving them access to a rigorous academic education. There's a fundamental flaw in this pitch: you don't see poor children in grammar schools. Fewer than three per cent of children on free school meals are educated in grammar schools, compared with 18 per cent nationally.
Where they still do exist, grammar schools are dominated by children from affluent families whose parents can afford the private tuition to coach them for the 11-plus.
I know this to be true from very personal experience.
My daughter, now all grown up, was 10 when we moved from Yorkshire to Kingston-upon Thames in south west London, a local authority which retains two grammar schools. On her first day at her new school round the corner from our new house I met her classmates’ parents at the school gate. Two quickly took me aside and advised me to get in touch with private tutors to coach my daughter for the 11-plus. I declined to do so and was accused of playing politics with my child's life - an accusation so bizarre that, perhaps for the only time in my life, it rendered me speechless.
The teachers in my daughter's school told me that it was not the most able children who passed the 11-plus but those who had been coached to within an inch of their lives. The Tories know that coaching is a fundamental problem for their argument that grammar schools promote a meritocracy - so they try to get round this by envisioning a test which can't be coached for - knowing full well that such a test does not exist – Buckinghamshire County Council tried to create one and failed.
Grammar schools do not work now.
In Kent, one of the few areas that has selective schools, children from low income backgrounds do worse than anywhere else in the country. The effects of segregation do not stop when pupils leave school; they are life-long. The model that the government should be looking to is not Kent, but London where the comprehensive schools outperform Kent for children from every social background.
Expanding grammar schools will make the biggest failing of the English school system - the large number of people who leave school without good qualifications - even worse.
Can it really be possible that it is this government's intention to harm educational standards for the majority of children in our schools?
The other argument that ministers will peddle to try to justify the unjustifiable is that there is already selection in the school system. But, if Theresa May is seriously worried about selection by the back door - through buying houses in the right postcodes - she should expand school catchment areas and allocate places at oversubscribed schools by a lottery, or by a fair banding system.
She should also take admissions away from individual schools and return the responsibility to local authorities who would enforce a fair playing field for pupil admissions.
Theresa May must not be allowed to get away with her fantasy vision of 'inclusive' grammar schools.
All is not lost
The whole point of grammar schools is that they exclude and they label the majority of children, aged 11, as failures. Nor can she be allowed to get away with the claim that she is extending parental choice - for those parents whose children fail the test, what choice do they have but to send their child to a secondary modern - even if it is not called by that name?
The range of informed voices opposing grammar school expansion is impressive. Theresa May has, at a stroke, managed to unite the Labour Party.
Ranged against her proposals, also, are influential figures such as Ofsted’s chief inspector, Sir Michael Wilshaw, who has condemned the idea that grammar schools are the answer to social mobility as 'tosh'. Alan Milburn, chair of the Social Mobility and Child Poverty Commission, has said grammar school expansion would be a disaster because it would not lead to selection by ability but by social class.
However - and this is important - all is not lost.
Reintroducing grammar schools will require legislation. Theresa May has a working majority in the House of Commons of just 17. It is an open secret that Tory MPs are uneasy and the House of Lords will not be constrained by the Salisbury Convention - that peers will not vote against a policy which was in the ruling party's manifesto - because overturning the existing legal ban on new grammar schools was not in the Tory party manifesto.
A senior Cabinet source has questioned why Theresa May has embarked upon such a risky policy as her first act of domestic legislation. She may live to regret looking forward to a rosy past of grammar schools.
Dr Mary Bousted is general secretary of the ATL teaching union. She tweets as @MaryBoustedATL