No probs - I used this one - bought new OEM from e bay £11 inc post.
Land Rover & Range Rover Remote Fuel Pump Inertia Switch, WQT100080
It uses a plug which I bought easily at a local auto / boat / caravan electrical outlet.
It feels like it has a steel ball inside poss held in place by a magnet, when it gets a good knock the ball dis lodges and breaks (or makes) the circuit. Mounted in the car behind drivers seat so as to be easy to reset.
Reset is simply a case of pushing a button on the top of the unit.
Didn't fancy the facet busily trying to empty the tank in the case of a knock, as it runs constantly with ign on, also the inertia switch would kill the engine, after the carbs ran dry.
Slight concern re nuisance tripping but unlikely I think as (some !) land/ range rovers are rough service vehicles.
Will post if I have any problems with it.
Cheers
Steve