Ah ha! Well I hadn't a clue what either of them were for. Thanks chaps.

I too had a weird electrical issue quite recently: on turning the ignition key on my Plus 8 (but before pressing the 'start' button), the horn would sound. Gave up trying to fathom the issue but two days later (whilst waiting on advice from Williams and having returned to the car a few times), the problem disappeared. Strange indeed.

I'm off to play with my dimmer switch......

Bob
2016 ARP4 Porsche Prosecco
2018 Plus 8 Bentley Satin Grey