Its an interesting point, and since I use the car year round one that I hope to address, although as pointed out, on a 2003 car that reg hopefully doesn't apply. As you might imagine, the heater element gave up the ghost years ago, and the screen edge has permanent misting between the laminate. but has always passed MOT. The main reason for changibg it is the external micro pitting that causes problems in sunshine and oncoming headlights.
I am going to try heated elements in the screen surround channel at the bottom, or that failing, then a jury rig for winter from the two small outlets on the bottom of the heater control box to pipe warm air along the bottom of the screen. I always carry a shammy!
