Candidates have from now until the next election to answer all questions
A Shadow Education Secretary promises grammar school education by means of streaming and setting inside comprehensive schools. How big would such schools need to be?
Under the old Tripartite System 25% of children got into grammar schools. Once in those schools, they were further streamed and setted according to ability. Since in a typical school there were three such streams, each one contained about 8% of the age group in the overall population. So the comprehensive has to be big enough to allow classes containing no more than 8% of the age group.
Since the average secondary class size today is 21.7, that implies the school needs at least 271 pupils in each year (equals 21.7 x 100/8). Five year groups at 271 each equals 1,355 pupils up to age 16. Assuming one third stay on for two years beyond 16 (the current average), that adds another 180. Which means the overall school size is 1,535.
Is that too big?
Consider the independent schools, where it's customers rather than politicians who determine what happens. None are this big. Even Eton, one of the very largest, only has 1,350 boys. And Eton selects its pupils with great care, ensuring that they are all fairly similar- not only proper toffs and rich (fees £26 grand pa), but also, these days, highly able. Indeed these days, it is easier for a camel to lead the Tory Party than for a stupid toff to get into Eton (well, obviously really REALLY blue blood still trumps IQ, but that's only to be expected).
Education is not some technical issue like tractor production, where Big may be Best. All our experience with those bog standard comps surely tells us that 1,000 is already way too big. And it's hardly Soviet rocket science- parents know it in their bones, which of course is why concerned aspirational parents always choose small.