Where did the name come from?

It was thought up in an exercise conducted by the two founding members.

Apparently, they chose cats because cats 'sing' - howl at the moon, whatever - just for the pleasure of it, and they needed an adjective to go with it to make the name.  Rodger did a visualisation exercise with Adam, got him to imagine the group as he hoped it would become, and then asked him questions to help conjure up and clarify what he saw.  One of the questions was what colour was the choir in his mind's eye, and Adam answered purple. Apparently it was meant to be a bit of a silly name - distinctive, memorable and fun!

So there you go!