In reply to The Mystery Toad:
I have both ends of the wiring loom and was hoping to get "connect left indicator ground to X" etc. I've decided to throw caution to the wind and as Pins 1, 2, 4, 5, 7, 8, 10 all seem to map to their corresponding position on the opposite end of the loom I'm going to gamble that 3, 6 and 9 follow the same pattern
A quick bit of contact cleaning and then I'm going to reassemble it, so if you see "Man dies in inexplicable French car catastrophe" in the news tomorrow then you'll know I got it wrong!