I got home tonight wondering why the guy behind me nearly drove into the back of my car when turning into the drive.
Found out the brake lights were permanently on, they flickered when the brake pedal was tapped. After some rooting around i found the switch is in the passenger footwell (ah the logic of french cars!). Usually the switches are screwed in and out to adjust but not here they push in
The cable that runs to the switch hangs quite low, so theres a good chance that the cable could be pulled by the passengers foot/feet. I assume thats what happened here.
I wonder how long they have been like that...
No dramas but thought this might be useful to someone one day!