It's unlike me, but I'm sick of this project now and I'm going to offer it up for sale to anyone who thinks they can fix it.
I unpacked my new ECU, Key transponder and immobiliser unit, and installed it all in the car today. Not a sod of difference I'm afraid. Still no EML and No spark. So - I change the engine management loom which involved lots of crawling about. No joy. same symptoms. I put some fresh earth straps on the body and engine - no difference.
Then checked all connections, and went back inside the cabin. I noticed that JUST the EML was on! I then looked at the engine bay, and to my horror my New ECU had somehow fallen across the battery terminals and had caused a short. So that's probably buggered now.
Even though there are no lights at all on the dash (engine still turns over) - I can still hear the relays making a noise in the ECU box.
Although the car is mint, this has gone far enough for an N reg 2.0, it's cold and dark early, and I've given up - if there are no magic suggestions, it will be sold as scrap tomorrow