That can't really be anything other than a slipway for the old ferry, can it? Especially as there are steps down there from the road, albeit overgrown to the point of invisibility and with their entrance bricked up, as we'll see when we get to the other side.
This bridge was only put up to replace the ferry in the 1930s, so it's not surprising that the ferry facilities are still pretty obvious from this side.
We have, in fact, wandered down there on a previous walk.
GPS Coordinates:
51.44606, -2.59873
Location: Wapping Wharf