As I said above all contact points were perfect and I also checked resistance values and continuity of all filaments and current paths, all were good, but I did make sure with a little wire wool treatment.

However, the good news is that I've managed to locate and rectify the problem, and it's got nothing to do with electrical contacts thankfully. The last time I fired up NavCoder I made a couple of coding changes in the Light Control Module, and one change must have been to enable bulb-checking on the rear high-level brake light; nothing untoward happened at the time hence the reason I didn't pick it up straight away as being the problem, but the high-level brake light is a string of LEDs, and as we know LEDs often cause problems with bulb-check modules. This was therefore the cause of the "Check Brake Lights" warning.

My attention was initially drawn to the high-level brake light because when it was on I noticed it was very slightly pulsing, which I knew was the bulb-checker doing its thing, so I decided to get rid of that by disabling bulb-checking on it. Hey presto, after recoding the LCM to get rid of the pulsing I found that the "Check Brake Lights" warning also disappeared.