This is the Jubilee Bridge Underpass, a walkway under the Croydon Flyover. It was painted with scenes from the nearby River Wandle in 2012, as a way of brightening up the area after the riot in 2011.
I like the murals, they do help brighten up an otherwise grim and scary place to walk at night. The cycle path marker reminds me of one near me where at one end the left is marked for pedestrians and the right for cycles, but if you go to the other end, instead of reversing them they are identical.........so confused people get half way along and find they are in the wrong lane!
