Daughter came home the other day and said "Why did my brakes not work?"
Digging as little further, it transpires that she was driving along, went to brake, and the pedal hit the floor. Slowed down, braked again and they worked.
Had a look this morning and thought "Oi oi, pads are getting down a bit!." so got some new ones and fitted this evening. This is what came off.
So, looks like the pad material on one side has let go and buggered off, leaving a fair old gap to make up on the next pedal press, then it went down to metal and contact made, and the brakes worked again. So new pads & discs fitted and all working again.