NER class 4CC No 731 with an up express prior to WWI at Low Fell. The signal bridge (the correct term for Gantry) in the background gives it away, if you look closely there is an upper quadrant co-acting arm underneath the signal bridge and it's on Low Fell's Down Fast Distant, No.66. This was needed for sighting below the overbridge (No.245) in the foreground. Of course UQ signals were very rare on the NER and only used when clearance or sighting made it absolutely necessary.
Robert J Purves who was at the time a draughtsman in the Gateshead Signal Dept drawing office. He must have had a nice camera and there are several of his glass plates still in existence. OSN reproduced several Purves shots in his books.

Photo: R.J. Purves/O.S. Nock Collection/RAS