I think you get £ from the L key if you hold Ctrl or Alt, can't remember, hang on...
Yep, it's Alt-L, that produces £, also Alt-A gives me æ, Alt-S gives me either ß or β, Alt-D gives me δ, and there's a variety of other letters and symbols accesed via this method.
I don't know why your keyboard would default to producing the `Alt-` versions of the key-presses.