GNR class O2 2-8-0 No 478 comes up the GNR main line near Hatfield or Potters Bar with an up coal train in 1923.

Francis Knight says "I'm not convinced by the stated location(s).
This looks like the approach to a 1-2-1 bore tunnel nearer to London. The outer (slow) lines are characteristically higher than the mains, presumably to minimise any extra cutting excavations needed when the line was expanded from two to four tracks".

Photo: Robert Brookman/Rail Archive Stephenson