My thanks to everyone here. To clarify, the engine ran fine a week before, and although old in shelf-years has perhaps 5 starts and 30 mins total run time. The battery is fine and I have also tried starting from an external DC power supply with no change.
It looks like the starter is the most likely culprit, so diagrams, vids etc which shed light on starter maintenance will be greatly appreciated.
Dave, what were the issues with the prior cable set?
Thanks again,
Don