Hi, Thanks for the incredible answer!
No tracker fitted, it was a run around that sat for over a year before I got it. I ran out first thing this morning and pulled the switch unit out, the process was exactly as you described.
All the cables looked good and there wasn't any flickering when they were wiggled, what I did notice was the fog light would flicker on and off when the switch itself was wiggled. Going to order a replacement for the sake of £10.
The answer and the welcome are greatly appreciated!