Just an update. AstoN_B you were spot on! The earth connection from ECU to batt was faulty. Small break in cable. Repaired and pump primed. Took a bit to get her going and was a little rough. Few trips round the block and the ECU settled down nicely and learn't the pattern. Now purring like a kitten. Well chuffed!
Head rebuilt and now for the body work inspection and respray, then retrim etc etc.....