The last few outings in the wedge have seen the starter motor a bit reluctant to fire up on the key. Yesterday it decided not to spin at all, luckily it was in the garage at the time.
Out with the starter motor, a lovely job with a V8, a nice tight fit next to the steering column and exhaust manifold. Jump leads were connected and the solenoid and starter motor both worked fine.
I removed the ignition module 218959 https://rimmerbros.com/Item--i-GRID006237 from the steering column. The casing was loose, it looked like a PO (there were 5 of them pre 1996) had opened it up. The casings metal tangs were misshapen. A quick call to Steve at S&S and a replacement item arrived the next morning and all was well again.
Amongst the original item's innards are 3 small coil springs, a tiny ball bearing, a circular spring, a copper plate of contacts etc etc. Good old analogue technology from the 1970's and I couldn't reassemble it in the right order if I tried.... photo will be posted if Imgur works with an IPad.