What does the law say about stickers on the windscreen?

Question:

Does the law stipulate the amount or size of stickers that I might have on my windscreen?

Answer:

Regulation 202 – you may not have stickers on the side and front window of your car and the back window may only have a sticker that does not cover more than 1/8 of the window.

Also view:

Road Safety and Your Windscreen

Is it better to repair or replace a damaged windscreen?