Thank you Tony, Mark and Lee for your responses. Yes, I think I do need to retire after that one.

Well, went back again. Seemed to spend too long actually locating modules but...cleaned (that is, sprayed with contact cleaner) EPS (Electronic Power Steering) and Instr. Panel/Body Electrical connectors. Cleared remaining fault codes and drove around the estate again. It remained clear of codes so left it for the garage to test. I forgot to scope the alternator output due to being overwhelmed by feeling of euphoria and elation at being code free!!

It did raise a number of still unanswered questions. According to the block diagram the Canbus (hi-speed) 'chain', as seen from the diag. socket, was through the BCM (called the instrument panel/body electrical), through the EPS (power steering), then some modules hanging off the bus on 'stubs', then through the ABS, with the ECM at the end. As I had continuity from the diag. socket through to the ECM, and a proper waveform at the socket, it seemed all the wiring was intact! I still don't know if modules 'talk' directly between themselves, or if the BCM acts as the mail-room and gathers and re-directs messages between modules.

I left the car error free, and I haven't heard from the garage since so perhaps it's a fix. I guess I'll know for sure when I get paid!!

Nick