Thanks for your replies must be a gremlin. I tried pressing the inertia switch to perhaps reset things but what happens is that the car is totally isolated with electric power which is what would happen in a collision and you have to physically reset the mechanical switch to restore power, but the light is still on unfortunately.
Have you tried tripping the circuit breaker on the front of electrics box. I know some owners use this to save the horrendous battery drain when car laid up for more than a few days.
Apologies if that is what you meant by mechanical switch.
