This kind of harness (right) was in use from the beginning of the 19th century until the middle of the 20th for horses who had to work with heavy carts on the land or in towns. The broadly padded saddle, with its channel for a ridge chain carrying the shafts, gave plenty of load-bearing surface to save the horse's back.
The museum also has a pit pony saddle of similar type (left), which was found in a peat bog by Mr Douglas Kent. Mr Kent was taking some boys camping near Middleton in Teesdale, and as they dug into the peat to sink their "loo" they came upon a perfectly preserved saddle only a few inches below the surface - only the horsehair had gone. A brass disc with the maker's name responded to cleaning: he was J W Walton of Middleton.
These saddles are made to carry the weight of solid cart shafts. Compare these heavy saddles with the plain backband used with the snigging horse (right). He wears the same simple harness as a plough horse. Neither of those jobs requires the horse to bear any weight on his back.