The facts are these: secondary education in inner London is not, as a system, “comprehensive” and never has been; it is both diverse and highly selective. If inner London schools are classified by what they are, rather than by the names they are entitled to put on their notepaper, the 15-plus age group of some 19,500 pupils breaks down very approximately as shown in the box (below).

For the benefit of excitable leader writers especially, it still seems necessary to explain the terminology that has to be used if analysis of what is happening in London - and, indeed, similar areas elsewhere - is to be carried out with any precision. Briefly, a “selective” or “grammar” school takes its pupils from the top 25 per cent of the ability range, measured at the point of entry to school.

A “secondary modern” school, however much it might wish to do otherwise, is one which in practice receives only the occasional pupil within that top ability range. A far higher proportion than 25 per cent is, of course, capable of achieving grammar level standards (that is, five or more GCSEs at A-C) but, unfortunately for them, secondary modern schools in London tend to have entries heavily weighted towards the bottom 50 per cent of the ability range.

A “comprehensive” school is one that receives, in something close to a ratio of 25:75, both grammar and secondary modern pupils.

“Other” schools, to use an old Ministry of Education term, are schools with an intake that lies somewhere between that of a comprehensive and a secondary modern school; for example, schools with an intake of between 85-95 per cent of secondary modern pupils and the remainder from the top 25 per cent of the ability range.

Terms such as “other” or “secondary modern” have to be used in any serious analysis of what is happening to schools to avoid the casual, but absurd assumption that any school which is not selective, as defined above, must therefore be “comprehensive”. Intakes vary somewhat from year to year and so there is movement, up or down, between categories.

But what is happening to inner London schools within each of the four categories? The 26 fee-paying, independent schools include some of the best schools in Europe. As a group, in a few cases topped (propped?) up by assisted places, nearly all these schools are doing well, at least in terms of their academic performance. How could they not be? The 23 schools which, for the purposes of this analysis, I have rather unkindly described as “secondary modern”, are now receiving the full force of ill-informed press hostility.

As I have been saying for more than 20 years, such schools are no more failed comprehensives than a Brussels sprout is a failed cabbage. They are something different, often situated in increasingly dangerous and deteriorating parts of the inner city and, particularly if they are boys’ schools, extraordinarily taxing to work in or manage. In short, these schools are still in trouble. In varying degrees, because some are plainly out-performing others, the 49 or so comprehensive schools are also doing well, with the 5-plus GCSE A-Cs usually above - and sometimes far above - the national average of 43.5 per cent.

When it comes to advanced work, the school chosen by Labour’s Tony Blair for his son, is a case worth looking at. Last year, 120 members of the London Oratory’s sixth form achieved two or more A-levels with a points score within a whisker of, for example, Marlborough College. The notion that well-run comprehensive schools, in London or elsewhere, cannot meet the needs of able pupils is simply false. They are the post-war years’ success story.

Of the 53 “other” schools, most appear to be doing well with what they have. Lacking such a high proportion of the top 25 per cent ability group, for these schools to manage outputs of well over 25 per cent at five-plus GCSE A-Cs, as many do, is no bad achievement. But they are constantly at risk, if selection increases, of being pushed into becoming secondary moderns.

Of course, all schools, like the rest of us, can and must do better. Increasing the proportion of the age group going into existing selective or newly formed grammar schools, and thereby increasing the number of secondary modern schools, seems an unpromising approach; and there are limits to what can be done by each school pulling itself up by its boot-straps. So what can be done? It is to that question that I shall return shortly.

Sir Peter Newsam is the former education officer of the Inner London Education Authority