Sent a wake-up (ie 'connect to instruments via K line' instruction') to the malfunctioning VDO cluster as a prequel to reading the EEPROM using VAG +K Commander and it did just that. The cluster came back on line with the dials and driver information modules, along with time and mileage LCDs now becoming live. The immobiliser light came on and went out as it should and the engine fired. The vehicle had been off the road for months with the cluster always dead on reconnection and retrial on the car on several occassions, with the new potential replacement cluster coming 'live' ie all clocks and driver information lighting up if attached in the same way, but flashing a continuous 'immobiliser on' signal.
Thanks for all the advice. If a VDO cluster appears knocked out by a voltage surge, leave it off the vehicle, take the battery off the car and fully charge it ( I in fact replaced the battery as it was not charging properly) and a week later (in my case several weeks) try then reattaching the cluster, make sure the battery is fully charged, and send the 'wake up' signal (ie connect to instruments) by VAG +K Commander. It may start working.