John Bald is a former Ofsted inspector and has written two books on the history of writing and spelling. He is a Vice-Chairman of the Conservative Education Society.

My wife’s stepfather, Jack Graham, began work as a miner, and served in the Eighth Army during World War Two. He held every rank from private to sergeant-major, though not in the usual order. Reluctance to peel potatoes, when he felt it was not his turn, led to a spell in Colchester glasshouse. 50 years later, in Colchester, I taught the daughter of a senior army officer, and our families became friends. He had once commanded the Colchester glasshouse. My wife’s father had served in the 51st Highland Division as a driver. When we moved to Cambridgeshire, she became friends with the tree warden of our village, whose father had served in the same division – as a brigadier.

The key factors in this social mobility were opportunity, ability and determination. My wife and I attended grammar schools in the sixties, followed by grant-supported university courses and, in different ways, worked our socks off. Sir Michael Wilshaw offered similar opportunities to his comprehensive intake in Hackney, smashing the glass ceiling of low expectations and opening the doors to top universities. The best free schools and academies are doing the same thing. All of them group children in core subjects and languages according to their learning needs and abilities. They realise that if children are to move out of the disadvantaged circumstances into which they are born, they need to be equipped with the knowledge, skills and understanding – personal as well as academic – that more advantaged children already have.

This is what is meant by “closing the gap”, and it is a difficult task when children start schools two years behind the children of highly-educated parents in their social and mental development. The most fervent protagonist of mixed ability teaching has not claimed that it enables these pupils to close the gap, because they know that it is not possible. The conditions that lead to lower attainment pre-school are no less active and influential during children’s school career, and the gap gets worse on transfer to secondary school. Jean Chall’s “The Reading Crisis: Why Poor Children Fall Behind” showed that the key issue was the growing use of technical vocabulary, which enabled children from highly educated homes to make accelerated progress, while those from stable, but less educated families, fell farther behind. This gets to the heart of the matter – without high levels of literacy, pupils can’t compete with those who already have them. Numeracy is not far behind, as it is the basis of the mathematics of personal and public life.

Professor Diane Reay, of Cambridge University and author of “Miseducation,” does not address the issue of literacy. Her own social mobility, from coal miner’s daughter to Cambridge Professor, also began with her attendance at grammar school, and she repeats the point made by Conservatives before the last election that these virtually eliminate the attainment gap between rich and poor for those who attend them. Sir Al Aynsley Green, Labour’s first children’s commissioner, and Sir Thomas Allen, international opera star and Chancellor of Durham University, enjoyed similar benefits. However, Professor Reay’s book is, like that of most of our political opponents, an angry piece of work, and endorses the view expressed by the late Dick Copland, who in his words “cut out” Robert Richardson Grammar School, that grouping children according to their abilities simply brings selection into the building.

Robert Richardson Grammar School remains the clearest example of the clash between the idea of social mobility and that of equality. Founded by miners, and named after the local union leader and Labour MP, its motto Ad Meliora – To Better Things – summed up its aim of giving children more chances than their parents had had. Sir Thomas Allen, whose glorious career was the basis of the film Billy Elliot – the producers substituted dance for opera – paid tribute to Robert Richardson in his inaugural address as Chancellor, and invited his former music teacher to lunch. The others I’ve cited, with Professor Francis, who attended a comprehensive school and, by her account just scraped O levels, fundamentally disagree, and always will, for reasons that go back to the beginning of civilisation. Professor Dylan Wiliam, a former Deputy Director of the London Institute of Education, described it in a talk I attended as “corrosive”, and went further, by backing schemes designed to allocate pupils to secondary schools by ballot rather than parental choice.

There is no disguising the fundamental clash of values between these angry academics and the mainstream of British political opinion. Our survival in the last century owed much to the work of three individuals – R J Mitchell, Frank Whittle, and Alan Turing, all educated at grammar or private schools. Professor Stephen Hawking, lionised by the Left as much because of his disability as his science – which very few on either side understand – had his education in private and Direct Grant grammar schools, a kind of super-grammar with its own entry requirements in addition to the 11-plus. The achievements of individuals such as these are, in the view of most of us, essential to both national survival and human development. Holding them back in the interest of “levelling attainment”, as one of the wreckers of higher education recently put it, is both against the national interest, and a denial of human potential. Equity, or fairness, is essential, and we do not yet have it. Equality, in the tradition of the Japanese proverb, “the nail that stands out will be hammered down,” is anti-social, anti-human, and ignorant. Destructive. We should be grateful to our opponents for providing us with a clear choice.