Legal or not, street art counts as protectable art.
To get a property release, you will have to track down the artist. If they’ve signed the art piece, you might have some luck via Google. If you’re unable to track down the artist and have a release signed, unfortunately, we are unlikely to accept the content.
The legal position regarding street art and graffiti is a changing one, and while there remain some instances where we will be able to accept unreleased street art, increasingly, we cannot.