Thanks for the heads -up on the relay spec Richard.
Interesting to read that the relay has diode protection acting not only to protect the relay contacts from possible arc damage when breaking the circuit but also protecting the ECU from spikes further down the circuit interconnections..?

The relay on my starter motor circuit began to fail a while back, suspected due to arcing at the contacts, perhaps not an unusual fault on pre digital trads given the lack of diode protection and the possible level of back emf generated by the inductive load of the solenoid etc.

While every day has potential to be a school day, the problem these days is trying to remember that which I have learned...!.