Strangeness: From the Mail

Here's a weird one for you. I received the above in the mail the other day. On the flip side is my address, nothing more. I don't recognise the art and I can't think of anyone I know, who has my postal address, who would send such a thing. It was posted from Leeds, which again is strange because I can't think of anyone who lives, or even visits, there. Perhaps there is some dark portent hidden within the wiggly lines? Or perhaps someone I know went there for the day and decided to play silly buggers with me. Anyway, it is my mini Voynich Manuscript and there is a reward for the first person to decipher its meaning.