The Great Northern needed new locomotives to accommodate the growing freight traffic on the Metropolitan Line between King's Cross and the goods yards between Farringdon Street and Ludgate Hill. The particular challenges were gradients of up to 1 in 35, tight curves and several tunnels. Two locomotives were therefore ordered from Avonside in 1866, based on two others that had been built for the Vale of Neath Railway.

With four coupled axles they were exceptionally strong by British standards at the time. In order to be able to drive through the tight curves, the first and last axles could each be moved laterally by 5/8 inch and were reset by springs. Because of the tunnels they had a condenser. However, as they turned out to be too large for the Metropolitan Line, it is unclear how long they were actually used there in the time until they were scrapped in 1880.