Just came across this topic on another forum:
Disecting a BBC Micro keyboard keyswitch.
This is the Type 1 switch, which in the south-east at least is the only type I've ever seen. Someone here said that Cherry MX black switches are much better than the ones Acorn used, but I'm curious now which of the four types he was familiar with, as it's a perfectly decent linear switch, and not as stiff as the MX clear/black spring.
Interesting to see that the pins screw in!