Last night the surface mounted spots in my bathroom and the LED lights in the room next door flickered, buzzed and then died. No other lights were effected and the fuse (RCD?) didn't trip. Trying them periodically they would occaisionally buzz, flicker and even come on briefly. until they finally died. There is no apparent damage/water leaks in the roof space. the light fitting in one room was changed a month ago. Where should I start looking for the fault?