I went to an SMschool in the 1960's.
I passed the 11+ I was in the top one percentile. My family moved LA's and therewas no grammar school place available for me in the new LEA we were told.
I was in a class of 40 in a smallish SM . The school had neither a good nor bad reputation. We had two form entry.
Discipline in the lower stream was poor.
Work ethic even in the higher stream was questionable and the general view was that no one should be a swot. No one should be academic and all should have prizes. This was student led but supported by the staff. No one liked a clever pupil.
Facilities were poor. Even our vocational facilities were pooer than the grammar school.
Allowing for the fact this was a school for those of a "practical bent" this made the notion of vocational education or practical education a nonsense.
That is of course assuming that the selection system was successful in identifying candidates for the appropriate schools.
That is questionable now as then.
The school took CSE . I took O levels because my parents paid for me to go for private tuition for them. It was not school policy to take O levels. The local grammar schools did those.
The grammar schools also had sixth forms.
My school was 11 - 15. Staying to fifth form ( in my day) was optional.
Out of the 40 pupils in my class 10 stayed to take CSE. The rest left at 15 and went to work in factories , shops and offices ( in that order - most to the factories, shops for the little more ambitious and offices for the " nice" girls and boys.
The boys who stayed on went into apprenticeships I went on to take A levels. I was the only one.
However, those who went to grammar school did not seem to fair much better. The top 5% took A levels as I did.
They had on average more O level passes than I did because they had that opportunity to take them. But that number was held by a very few. I did not have the opportunity to take a large number of O levels and amassed 8 CSE grade 1 passes and 5 O levels.
I was surprosed that many grammar school pupils did not do aswell as I did. many of them also took the CSE because they did not match up to the O level expectations. Those in the lower streams at grammar school were the ones who did the CSE courses.
A considerable number ( two thirds or more) left at 16 and joined my peers from SM in jobs in the factories, ( as few apprentices) shops and ( for the nice girls) offices. Many chose to try to get jobs in the civil service or local government as this was seen as being " better"
A few girls went into nursing. Some of my peers did that too. Some went into the police. So0me of my SM peers did that too.
Of those of us taking A levels - I was the only one from an SM. Two others did join me initially but left after a few weeks ( one stuck it a term) because the grammar school staff treated us badly. They looked down on us and I was given the distinct impression I should not have usurped my "position"
(SM lad).
However, I persevered. I took a rather larger number of A levels ( I had private tuition which I paid for with a Saturday job) . I went to a top university. Of my grammar school compatriates, the majority went to teacher training college having been selected out at the beginning of sixth form to take that route.
Of those who were in the top one percent with me, they went to exactly the same academic destinations as I did. They were the ones who like me, went into professions or became full time academics ( not school teachers -yes I know I do that now, but I was retired out of academics)
So, really there seems to have been little difference between SM and grammar school education at the end of the day.
I guess it must be qualitative in some way, but again, having done both, I cant see what grammar school had I didnt except smaller classes and less discipline issues .... oh, and snobby teachers.
Since the demise of O level and the changes in A level and the raising of the school leaving age so all took exams, the differences I experienced have probably been levelled out.
I am sure there are fewer differences now and fewer opportunities too regardless of the school. I worked for a time in a grammar school, you might be surprised at what goes on.
However, I always feelI missed out on my education and for that reason my DC will be going to an independent where I can assure myself he will be given small classes, good teaching and more than anything else he will experience a strong work ethic and be in an environment where it is "cool to be a scholar" no matter what your ability
Grammar school or comprehensive or SM, I am afraid state schools simply have too many political agendas on them these days.