We have a fog light

Following the helpful and complete debugging instructions from Mick (holding the fort while Mark is on holiday at Westfield) we now have a fog light hoorah.

We have also sorted a couple of other little problems.

Fog light wiring explained here (Mick's words)

The fog light circuit is as follows. The fuse is supplied by a blue wire, which is from the main light switch. This becomes live only when the headlights are switched on ( second position ) Then off the other side of the fuse the wire is Blue/Red. This is the output to the fog light switch. The other wire on the fog light switch, also Blue/Red, is then the wire which runs to the back of the car and ultimately to the light. In summary, Blue wire at fuse box should be live when main lights on, then the Blue/Red wire out from box should become live at the same time. At the fog switch, one of the Blue/Red wires should now be live, and as the switch is turned on the second Blue/Red wire should be live. From here the next check would be on the Blue/Red wire in the o/s rear light plug. If there is no power at this fuse then the most probable cause would be the connection on the bottom of the fuse.