Just a quick update. Fingers crossed , but it looks like a change in engine won’t be needed. The replacement ECU from Digital Tuning Solutions got the engine going again OK. And allowed the EWS module to be removed.
My original ECU passed all their tests when returned to them for credit. Which supports the theory that is was the remapping that was faulty rather than and actual ECU fault.
Thoroughly recommend them if looking for new ECU. Offer all the usual stuff; immobiliser removal, post cat lambda removal, SAP removal, ABS limp home delete. And various levels of engine tune.