Just a normal 12v relay, this is the one I bought

Then all you do is:
85 - Ignition switched live
86 - Switched earth from pin 56 (brown/black wire) on sierra stalks
30 - Feed from fuse box (ignition live)
87 - Feed to fog switch then to the light

Ah gotcha. I get confused with different colours, number of pins etc. Probably just one that I used to wire up spotlights to main beam years ago rather than fry light stalks by wiring them directly!