At my school, you have to pay for lockers, and you have to supply your own key. However, if you're a music student, you can get a locker in the music block for free, but you have to give a spare key to the head of department. According to what people I know from other schools say (friends, cousins, people from Girl Guides, ect.), the way lockers work at my school are completely different to the majority of other schools in the area.
