Mark and Dave, thank you ever so much, between the diagrams and the notes I feel like my job just got far far easier. Thank you very much, I can't do anything more today, but I can't help feeling that I'll sleep easier, without trying to work out what goes where at three in the morning.
I spent a couple of hours in a breaker's yard today. I have to confess that last time I was thinking about it, there seemed to be piles of metros. However today I could only find two, one that was appropriate but largely scavenged and a pretty well untouched Rover Metro. One of the things that struck me was that the Rover stalks look much nicer and are significantly smaller in place. Has anyone tried fitting one?
I do have one specific question which I was embarrassed to ask but that the breakers didn't supply an answer to as the bit was missing. At the bottom of the moulding for the bottom of the lights and indicators stalk, there is a heavy duty brown wire soldered onto what looks to be a metal plate that runs inside the base of the stalk mounting. As it is brown I assume that it is a live feed, but I don't know for sure, and I don't know where it is meant to connect to. There doesn't seem to be anywhere obvious for it to go and it has been cut to only about six inches long. Is it simply a live feed and is it supplying the stalk or coming from the stalk to supply something else?

