Answer June 2020
The clue image is of the cast iron door on the Sele Well, on the path up from Cockshaw. Apart from the trees and the foliage, it seems little changed from the image from 1906 which is in the Sele Gallery section of the HLHS Photo Archive.
The Well appears on the 1826 Woods Map of Hexham, and according the the Historic England website (link below) dates from at least 1823. The above map extract was from a survey in the 1850s and published in the 1860s.
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Thanks to Stefan for the modern images.