Having had the wheel speed sensor pack up, bodging it to get it working again and realising that I needed a new one, I got one of Andrew's (Bunny on here) long lead sensors which arrived today. This evening I steeled myself to fit the new sensor which was obviously a classic ten minute job and ten minutes after starting it was all fitted, cables neatly routed and secured and working as it should. I don't think this has ever happened before. No random rivnuts spontaneously started spinning, no other bits fell off, nothing broke and it all just worked. Very strange.
Thanks to Andrew for a good, sensible kit of bits to do the job.
The ten minutes does not include the hours poring over the loom diagrams and rummaging behind the dash trying to find the wire that I had obviously disturbed while fixing the indicator stalk button wiring that had come apart. The speedometer had packed up as soon as I had got the button working again so it took a while before I thought to test the hall effect sensor which had decided all on its own to fail as soon as I had fixed the other electrical gremlin, presumably out of spite.