Right, popped back to B+Q and changed it for an idental one, but this time it said min load 40w, max of 250, installed that one and it works perfectly

Last Q - red goes to L1, black to common, and L2 is vacant (was how it was before, and is now)

Inside the wall box where the spur comes in, is a grey cable - 2x red, 2x black and 2x green/yellow earth. Obvisouly red and black go to switch, and the earths are attached to the chassis/wall box.

My switch has a brass/metal screw bot on it saying it must be attached to "earth in terminal box"

But I don't have a wire for this?

Do I just need to fit a bit of electrical wire from the faceplate to the point in the chassis/wall box where the spur earths are attached?

There wasn't one there before, but I have had a couple static electricity shocks (usually if I am wearing my fleece and been lying on the sofa)