Brilliant! Thanks for coming up trumps.
Well, it could be by any of a number of photographers, D S Fish, Peter Gray, who were both local, R C Riley and, of course, Blenkinsop come to mind. There is that long gone bow spring bridge and the cameraman was just where I saw the train. I'm also interested that neither engine has the head board but the coaches seem to indicate it was the down 'Riviera'.
The photo was taken in September 1957, which counts me out as I was only eight then! The locos seem to have differing positions for the mechanical lubricators with the boilers not appearing to be the final versions that had a square cover patch high up between the top feed pipe and the firebox front on the side shown. Finally, 6017 seems to have had its tender topped up so I'm not sure that was the working of the Riviera and its relief. Any ideas?