I have 3 of my children at the same secondary school, and I am so fed up of PE kit vanishing.
Last summer term both DS's PE bags vanished. I bought DS2 a whole new PE kit over the summer holidays.Last term he had PE during the day, but when it was hometime he looked for his kit (which he wanted for local basket ball club)and it had disapperaed from the peg.Before the xmas holidays we went through absolutely everything in the cloakrooms in the cubbyholes and the lost property- nothing!
DD went to do PE on Thursday and found her bag unzipped and her PE top missing.
PE kits are supposed to be left on shelves in the cloakroom (completely insecure).The kids have lockers but they are too small to store PE kit in,and dotted anywhere around the school so no tim to fetch them before PElesson.In fact in the case of DS2, his locker is actually within a classroom so he has no access to it most of the time.
The kids get detention if they don't have their complete PE kit so I think they just go and 'borrow' them from someone else's bag.They never turn up agin though.
I have raised the matter with the school who although very understanding can't offer any practical solutions.