This seems like a good idea, but I hope it doesn't stop the recent tradition of yarn-bombing[0] the postboxes[1][2]. The ones near me are really creative, change with seasons & national holidays, and just add a bit of British whimsy to day-to-day life.

(Looks like there's already some articles on this angle [3]!)

[0] - https://en.wikipedia.org/wiki/Yarn_bombing

[1] - https://en.wikipedia.org/wiki/Post_box_topper

[2] - https://www.bbc.co.uk/news/uk-england-derbyshire-63833983

[3] - https://www.bbc.com/news/articles/cly9q5jwv18o