Not sure what caused it, just wear i think. I bought it from Brixton Cycles so will email them and how long ago it was, see if it is covered under warranty still
I think that's a known weak point, of the earlier Cambiums at least; IIRC there was a fair bit of discussion on the CTC forums about the failures at the time.
Don’t throw it out, that rear plate will be of use to someone.
It’s a c15?