231 would have been an Up train. Up trains had odd numbers; Down trains had even numbers.@6Gman, many thanks ...you have collated the direction of my thoughts almost exactly and @chief
Planner has very kindly answered them. I had not envisaged that there would be so much interesting information when I uploaded
the photograph!
...and ChiefPlanner, you suggested earlier that it could be the 231 down, where did this train originate (I presume it's
destination was Kings Cross)
Whereabouts was Niddrie and what happened to the yards there?
I can't find a 231 in 1955. I can find:
275 1935 C Niddrie-Kings X
251 0020 C Niddrie-Whitemoor
273 0020 C Inverkeithing-Kings X
255 0350 E Niddrie-Skelton (York)
257 1022 C Aberdeen-Kings X
259 1230 C Aberdeen-Kings X
261 1340 C Aberdeen-Kings X
271 1805 C Niddruie-Woodford Halse
279 1836 C Niddrie-Doncaster Decoy Yard
Which makes a pretty impressive set of Anglo-Scottish fast fitted freights!