Hello,
Well it's fixed....
So I had only tested for power after turning the ignition on with the indicator connected, the fault presented and there was no pulsing power feed. This led me to think there was a break somewhere further down the feed. For some reason this morning I turned ignition on as usual and the fault was there. This time however I turned the ignition off, disconnected the indicator plug and turned on the ignition. Checked for pulsing current and lo and behold it was there! Refitted the mirror unit and the fault recurred so it was obviously the CANBUS shutting down that circuit due to a fault within the mirror wiring loom.
So I had a spare mirror assembly that I had to replace after my recent spill so ignition off, connected, ignition on and indicator worked!. So a fault in the wiring from plug to bulb in the old mirror unit but at least I had a working piece of loom I could use. So after splitting the mirror casings apart and swapping over the loom in the mirror I plugged it all back in and everything works as it should.
All now good so just a few more bits to come back from repair and I will be back on the road again.
Thanks for the suggestions - They were pretty close! I will take away from this that if anything remotely similar occurs then unplug the failing part and then reset the CANBUS -Ignition off/on. If you leave it plugged in the circuit shuts down as soon as you turn on the ignition!
I suppose this is why they call it electrickery?
Best regards,
David

The Hokey Cokey. What if that is what life is all about?
BMW R1200S-2006 with much carbon,PCIII & Schnitzer,
Subaru Levorg 2.0DIT STi (JDM model) and an Abarth 595 MTA 180 Competizione Convertible