Rear fog light

[CountryGent]

Im back again,
seems right to ask here first!
So, fog light was working and now its not.
Checklist
1. Fuse 19 is fine
2. Bulb is fine,
3. Bulb holder and block connector fine
4. All other lights in the cluster work fine
5. Front fogs work fine
6. No towbar ever fitted

Clues for me people
Thanks
Lee

[jonsowman]

When you say the bulb holder and block connector are OK, is there 12V at the bulb-positive wire when the fog is turned on?

I've got a nasty feeling the fogs are BSI switched...