Headlight switch bulb

Does anyone know if it's possible to replace the bulb inside this switch?:



If so, where can I get a bulb for it?

Cheers gav.

usually tes, the bulb holder twists and comes out. not sure what type of bulb it is, some kind of mini wedge

I got one from a local motor factors, just took the old one in and they had one on the shelf.
P.S Halford won't sell it.