So Just an update....
Thanks to RichardM i was able to test the individual sensors and wiring with more detail on resistences etc. Now the most suspect item is the PCM - Power Train Control Module or ECU. I have learned that this is in harmony through the can bus with the immobiliser. So I am now in the area of trying to test or clone the ECU. The unit was sent to one well established company who could not test it. So, It is with another who do cloning by transferring the eprom chip to a doner ECU. That's the stage I am at at the moment, however upon dismantling the ecu, the main circuit board is covered in a jelly structure that is difficult to remove and see through. They dont know quite where this chip is so it is taking a bit of time. If anyone has had experience of cloning and where the chip is would be helpful. If this does not work I think I may have to get a whole set of ECU's and immobiliser and keys from a dismantler. It would appear that if this ECU was a bosch, they are relatively easy to clone and electronically disable the immobiliser.
Seems I am down a rabbit hole and may not get back out !!