The grey mount view is from the late 1850s and the yellow mount is about 1864 and by Francis Bedford. Apparently there was a relationship between George Swan Nottage, founder of the London Stereoscopic Company and later Lord Mayor of London, and either a contractor or architect of the Crumlin Viaduct - hence the stereoviews.
Kindly donated by Ray Norman. These stereoviews will be auctioned over the Christmas period - get more information by clicking HERE