Thanks Phil.
You obviously no what you are talking about. That was a really interesting and informative. The serial number on my gearbox is 0360305.
I will try disconnecting the electrical connection and see if that replicates the fault. I have also just purchased diagnostic software INPA and ISTA and will try these and see what sort of information I can pull from the car to aid with fault diagnosis.
What electrical fault would cause these symptoms and if it is a fault within the gearbox itself is it more economic to replace the gearbox or repair. I only ask as I have been offered a low mileage box complete with torque converter and transfer box for a very reasonable price.