I've had a really good look as I was sorting the inner CV boot out today, looks like it leads to nowhere. Everything appears to be working, Air bag light is on due to a know fault with the harness, that's on my list. Other than that I think it's going to remain disconnected.
I've attempted to look at the wiring diagram and refer to the coloured wires, still didn't get anywhere. Here's a few images showing location on the loom, length, a clip which I assume holds the cable and the fact it already has a kink which would make me assume it's been connected to something in the past.