Primary school 1969-74
Secondary school 1974-82
I was fortunate in 2 things.
1: My Primary School was 2 minutes from home - and during the time I was there my mother didn't work.
2: She had seen what they offered up.
I went home for lunch
Even then I can recall the horrid smell of boiled veg - with cabbage to the fore - and other things that could turn the stomach.
I know from fellow pupils that the food was consistently vile - some would regularly hurl their guts aftewards - many would look unwell. It certainly looked dreadful.
And they had to clear their plates. The on duty teachers might not insist on this but there was a "Supervisor" who would normally check pupil's plates before they left the table. She was a horrid woman (probably from central Europe - might well have driven a Panzer in WW2) with a permanent look on her face like she was drinking vinegar. She would force everyone to totally clear their plates - she even made kids eat what was clearly gristle. On Friends Reunited there were a number of comments on her - none even close to pleasant. Apparently, if you were clever (and maybe lucky as well) you could stick really inedible stuff into your socks and get past her - she would check pockets.
As a consequence I didn't have school dinners at Secondary School either. I was told by a couple of comrades who attended both schools that the Secondary dinners, although far from great, were much better. That school was 10 minutes from school so normally I would go home but sometimes took in a packed lunch - this would have to be eaten in the dinner room, and the smell wasn't all that much better.
When I saw Jamie Oliver offering up superb looking lamb tajine (seeing parents refer to it as 'muck' and 'rubbish' then passing bags of chips through the school fence - or insisteing they 'must' be given turkey twizzlers made me weep) and simiar for a great price made me wish such an idea existed when I was at school.
But then seeing a dinnerlady who had so little idea how to prepare pasta (yes pasta

) that she boiled it back to it's original state suggeted I missed nothing