I have had a bit of an annoying rattle, recently. Just going over bad speed bumps or really rough bits of road. With my MOT due in 6 weeks I started to contemplate what they would find, thinking drop links would not be too pricey!
Well the last couple of days I have been driving round with my "Air con" on (driver's window open, it is an S after all), and the rattle has stopped. Perhaps a cable or something is resting against the glass instead of tapping against the door.