Okay, screwdriver now packed away. My 30mins went as follows : both clusters out, both bulbs look fine, wiring looks complete, fogs on... Drivers side only. Swap the bulbs, fogs on.... Drivers side only. Scratch head. Swap bulbs. Same thing. Conclusion - computer setting ? Confused. Anyway, only took 10mins.
Spent the next 20mins getting the rear clusters aligned properly again because they are of course not a flush fit. What a pain in the a$$. Don't even feel I have done everyone a service because I am more confused than when I started... :x