I was in that experimental two years in the mid 1970's where they threw in a whole load of rough Comps in with a load of formally good Grammars.
After 4 Terms, one bit of serious arson, cancellation of all extra curricular activities, (all visits, all field trips, the award winning school band, the school play, all team sports, all special needs teaching, all detentions

and the school library)
We had 3 headmasters during the four terms, the first one lasted one term, number two suspended over 50 kids and was told to take them all back, he refused, so was fired, number three then presided over the departure of 88 of the 90 members of teaching staff.
They then chucked out my entire year as being 'unteachable'
No exams at all were sat that year, so we all left, aged 16 with not a single exam between nearly 200 of us.
Today it would be a scandal, then it was normal as I have fiends of the same age in different schools who were (and still are) in the same position.
We found out later, that headmaster number 3 invited most (but not all) of the ex Grammar kids back to do a special crammed 6th year, but they had mucked it up so badly none went back but a load went to the 6th form down the road who then employed a number of the ex teachers to do a crammed special year for them (with short holidays and extended days, seven terms crammed into three).
Like most of my compatriots we all went straight to work