The situation seems to have diffused now. I now know who actually did it, and have spoken to the school staff, who informed me that they have CCTV overlooking the bikes. After I told that to the guys who did it, no one has so much as sneezed at my bike.
Thanks for all the kind words/abusive suggestions/help, you calmed me a lot. I knew I could rely on you guys. Group hug?
(PS - Mrs Minx, thanks for the offer, but I already have a disc lock, as well as a chain and an alarm lock. Plus, I couldn’t take it. I’d be denying you precious smackers from a sell-on :P)