This view is taken from the top of the Bell Ironworks blast furnaces in Port Clarence. The two men would have had the job of charging the blast furnaces, dropping iron ore, coke and limestone into what is called the bell. I would guess that the furnace at this time would have been off line.
There is a ferry, halfway across the river, in the middle distance. This would have been at the location where the Transporter Bridge now stands. The Clarence Railway comes in from the Stockton direction, on an embankment (which is still there), and then splits into branches serving the blast furnaces, salt wells and tar distilleries. But it is possible that the turn off to the river is where the original staithes at Port Clarence were built. The buildings near the railway bridge (hard to make out) , which goes over the road leading to the ferries, would have been part of the Port Clarence railway station.
Image and details courtesy of Fred Starr.