Advertisements and shop signs
An advertisement means any work, letter, model, sign, placard, board, notice, device or representation, whether illuminated or not, in the nature of and employed wholly or in part for the purposes of advertisement or direction (excluding any such thing employed wholly as a memorial or as a railway signal) and includes any hoarding or similar structure used or adapted for use for the display of advertisements.
More information is available from the planning portal - adverts and signs and in the GOV.UK's guide for advertisers