This irrational expansion would boost staying-on rates he claims, despite the fact - well-known surely, even to a lobbyist for schools - that "non-traditional" students are far less likely to stay on at schools than move on to colleges.
Sir Cyril argues rather more persuasively for co-ordination between schools, colleges and sector-skills organisations, to offer a range of learning to suit various types of student. Unfortunately, this vision is utterly incompatible with his anarchic call for all good 11-16 schools (however these may be defined) to "have an absolute right to offer post-16 provision".
Opening a school sixth form unilaterally can quickly damage or close existing providers, including ones offering a better service. It can even produce the ridiculous situation where a subject cannot be offered locally, even though there is demand for it, because no one provider has enough students.
Many investigations over the years have shown that the most academically successful provision is that offered by large school sixth forms and sixth-form colleges, followed at some distance by general FE colleges.
Small school sixth forms inevitably come a poor fourth due to inexpert teachers and a narrow range of subjects - even though, as Sir Cyril rightly notes, colleges are handicapped by receiving less funding than schools.
Small sixth forms can certainly have their place, run in partnership with a college or a larger school, but they have to be planned for.
Many of us can think of examples where excellent colleges are threatened by the so-called strategy of allowing 11-16 schools to open sixth forms or of replacing some with 11-18 "academies" - a policy that will lower attainment and increase the cost of education.
To avoid such daft outcomes, ministers and quangos will have to do some joined-up thinking and avoid Sir Cyril's one-size-fits-all, bog-standard policy of opening school sixth forms regardless of their circumstances.
Dr Michael Sherborne
6 Wychwood Avenue