I believe this photograph to be much later than listed, 1951 would be a better option.
All the locomotives visible seem to be carrying Gresley LNER style boilers (post 1923)and at least two on the locomotives on the left appear to be L1 type locomotives introduced in 1945.
The locomotive in the centre facing the camera appears to be a class B1 or B2 locomotive, again post 1923.
Although not clear the first locomotive on the left appears to be carrying a British Railway Lion and Wheel logo (1950s) and the locomotives facing the camera appear to be carrying smokebox number plates another post nationalisation (1948) feature.