Again many thanks to everyone concerned.
I dont think the immobiliser is the issue as red light/beeping signal does change as and when the key is in the ignition, and I did try the “change of key approach” with no joy. This leaves me with the fuel relay and a new challenge. Current fit is a 3 pin Wehrle 54 201 101 with blades marked 49, 49 and31 but I can only find 4 pin replacements. Looking at Berrybrook they suggest/recommend a Bosch 4 pin but assume this wont work as only 3 sockets are wired ?
I will speak to them next week to see what needs to be done but as electrics and me have never got on it may be I need to find an auto electrician.
Are you absolutely sure that you have identified the correct relay for the fuel pump?
3 pin seems peculiar and as you can see its on ebay,it is used as a flasher relay. I would expect the fuel pump relay to have at least 4 pins…2 pins for relay coil and 2 pins for the pump supply.