Our school was too shit for a band.
That, basically (although our 6th form beat the local grammar, that’s no longer a grammar, at A-Levels, up to just after I left when it then got put on report by OFSTED).
If one is allowed to count the boys and girls grammar schools as a single school, then my mother’s school band was The Rolling Stones. An my cousin’s alumni include people like Nana Moon and Gemma Arterton etc.
I honestly cannot think of anyone from my school that was even remotely famous. And wikipedia seems to confirm. That’s true for the primary, middle and upper schools.
Uni, however is totally different, and that list of famous alumni is almost endless (although I can’t think of any that were bands). And a colleague’s sister was Millie from This Life. And my dad used to drive Jools Holland up to town. I can think of more tenuous than that, too.