LONDON – The next time you're out and about in Britain's capital, make sure you keep your eyes peeled for stencilled messages or unusual billboards.

An unnamed graffiti artist's amusing collection of subversive street art has been photographed by the anonymous Mobstr, who runs a website which, according to the disclaimer, captures "images of work found on streets and other locations by persons unknown". Mobstr, who gave Mashable permission to re-publish some of the work below, told us that a lot of the art has since been removed.

Mobstr says he became interested in this type of art when he was around 11 years old. "I found a sheet of stickers, the type you write addresses on and stick onto envelopes. I decided to write on these quotes, phrases and tags that I particularly liked. I began sticking these up around the place.

"I can’t remember the exact reasons that brought me to doing this but I think I liked the idea of discovering hidden musings within your environment."

Mobstr Street Art

When we asked Mobstr if the person behind the art had ever been caught, he mentioned "an arrest in 2003 and some other close calls down the line."

You can see more of Mobstr's work on his Instagram and his website.