Most school histories shy away from criticism of former heads and teachers.
It's to the credit of John Cornwell, then - and to King Edward VII School, Sheffield (KES), his subject and publisher - that when punches are called for, he doesn't pull them.
He's not happy, for example, about Nathaniel Clapton, head from 1959 to 1965, who permitted not only formal caning, but the casual hurling of board rubbers and books at pupils: "The headmaster must be judged culpable of not rooting out physical punishment, often of a humiliating nature... even in the Fifties this was clearly quite irresponsible behaviour."
Clapton's methods came at the end of an old order. As KES moved into the Sixties, it was swept up by tides that saw it change within a short time from a grammar of 800 boys into a big co-educational comprehensive.
Cornwell's detailed examination of the accompanying furore is a reminder of a time when political decisions - and opposition to them - were based on principle.
But then the school was born out of high-minded politics. The Education Act of 1902 allowed counties and county boroughs to fund secondary schools, and it took only a few years for Sheffield to decide that it needed a prestigious local authority school to rival the grammar schools of Leeds, Bradford and Manchester. The education committee achieved its aim by funding the amalgamation of two existing schools: Sheffield Royal Grammar and Wesley College, founded in 1604 and 1838 respectively.
From then, the story for many years is generally one of stability. When the founding head, James Hichens, died in 1938, the school had not changed much since 1905. And much later: "If Hichens had been able to return in Nathaniel Clapton's final year (1965), he would still have felt instantly at home both in the building and in the classrooms. The staff, entirely male and predominantly Oxbridge graduates, still strode the corridors in their gowns."
But what about today? "Virtually all the institutions that defined his school, and were considered so vitally important for its effective progress, have disappeared in the last 40 years. Speech days, formal morning assemblies, head boys and prefects, uniforms, houses, corporal punishment, classics."
At the heart of it all, as Cornwell reassures us, is a good school of which Clapton would approve: "As a fair-minded man he would appreciate how the modern KES was successfully educating so many pupils of such widely different abilities and backgrounds."