Mr Farrant, Sir, you are bang on once again. Having dropped the sump and cranked the engine over (trapping a finger in the process OUCH!), I could see the oil pump shaft was not turning:nut:.
What can I say? I know I am among friends so can admit my mistakes. I recall when removing the dizzy, undoing BOTH set screws and lock nuts, I guess at this point the oil pump slipped out of drive.:blush:
I am not a mechanic, just a Builders Yard Foreman/HGV driver with (most of the time) enhusiasm.
Anyway I now have around 25psi oil pressure on tick over and all is well with the world again:-D.
Thanks Rivet for your encouragement too!