Also groom - where is that description from? "The beach (foreshore) is in front of the Royal Festival Hall Access by stairs either side of the Festival Pier. ...and yes, there is sand along with the pebbles."
I think it looks a lot like stairs down to a Thames beach, and I don't see why it can't be the sun shining from the west if they are facing north, which would make it afternoon-ish.
Thanks
Chris