Thanks for your replies you two,
The 2 gauges have still been doing the same thing everyday now without fail whenever I turn off the engine since my first post but the car has still been running fine all electrics inc. central locking all still work fine. The only thing I have noticed is that say after a long drive i.e. around 50 miles and then turn off the engine, the 2 gauges will go back to their normal resting places and stay there for around 3 minutes before springing up to the half way position again and stay there until the next time the engine is turned on. How would I go about checking the earths myself?
Thanks again - Liam
How have you gone on with your gauges as I have the same problem.