Tugger,
If you don't mind experimenting a bit, you might try this circuit. It's very generic and simple. Hardest part will be finding the corresponding 'UK'/'USA' parts (only 'touchy' one is the SCR). The majority of the parts are 'dirt' common, nothing special at all except for the 'sensor', sort of. It's usually made form an etched circuit board, but can be almost anything within reason. The 'contacts' must be closely spaced, but NOT touching! The switch(SW) is nice but unhooking the battery does the same thing. Nothing is to 'scale' so the finished size of the sensor is variable, whatever works. Same for the board the other components are on, how ever you happen to assemble them is fine.
- 'Doc
please excuse the drawing.