there were quite a few BBC Masters at my high school from 1986 onwards (replacing Model B's).
The numeric keyboard had * and # like a phone (for viewdata). They were networked, I coded a RAT using one which I concealed using the start screen of a legit wordprocessing app, a * would reload the (legit) WP screen (if a teacher was watching), # was the RAT control menu (it could even look into keyboard buffers of any other machine and thus obtain passwords) 😆 🐀 🕵🏽