Hi Everyone. I wonder if anyone can suggest what's going on in my Focus

It's a 2005 Focus 1.6 Zetec and I've had it for three years with not a problem.

Tonight though I was stopped at the traffic lights and suddenly the interior light came on by itself. I managed to switch it to the fully off position. Then I noticed that the indicators had stopped working. Also noticed that the Brake Warning Light was on.
Finally when I'd got home I tried to open the boot to let the dog out and that was also not working. Fortunately he could get out by folding the rear seat down!

It seems odd that all these seemingly unrelated problems have just suddenly occurred.

I'd be very grateful if someone can advise or make suggestions.

Thanks in advance
David