I sent the ECU of for test and repair and sure enough a fault was found on one of the coil drive outputs (Toyota IGT signal). The most likely cause of this fault I was informed is continual running with a misfire cased by a faulty coil. After "interrogating" the customer this was surely enough the cause. The interesting thing contrary to Toyota is that one ign coil drive signal loss caused all of the injectors to shut down, possibly due to the fact the car was driving until damage had been done to the ECU.
My thanks to David Davies for his info and insight and to Avilec for their test and repair.

Mark Robins