Found this outside the bus stop on South Street in Exeter, fortunately a someone at work was able to photograph this as my camera ran out of battery! Thanks Giles! It was quite the talk of the office, although I've seen quite a lot of this type of advertising in photos across the internet I've never seen in Exeter.
Curb, the Natural Media Company http://www.mindthecurb.com/what-we-do-snow.asp is at the forefront of some amazing natural graffiti/advertising and I look forward to seeing more of this type of advertising as it's natural, beautiful and exciting!
If you see anything of this kind in your town I would love to you to mail it to me.