Hi, I have just finished the wiring of my front fog lamps, and have followed your excellent How-To. Everything works perfectly, many thanks! The wiring diagram was especially helpful, and the switch pin guide was great, given that my car has no loom, so no green connector. I used "bootlace" pins, which slid easily over the switch pins, one at a time. If I can get hold of a connector in the future, I will change it out, but works for now.
I broke into the LH sidelight wire (as diagram), used it with a spur for pins 1 and 2. Pin 5 (earth) was taken to the radio earth, not the window. It does mean if the radio earth fails then the fog lights do to, but it seemed an easier wiring for my car.