New rear discs, pads and bearings ordered.
I had a look at the rear bearings yesterday as they have been groaning slightly, but having jacked up the rear there was no play present in either side at all. After reading around I found that the nut should be finger tight only and there can be a tiny amount of play present.
Well mine were done up stupidly tight, so i'm guessing there has been play in the past and that they've been tightened up, or they were over tightened in the first place which has caused the bearing to fail. I backed them off a bit until they were finger tight which introduced a slight amount of play, but after a quick roadtest it appears that they're definitely gone, so they're being replaced asap.