2-6-2T "Mountaineer" was built in 1916 by Cooke Works of the American Locomotive Company (ALCO) for the British War Department Light Railways. After the First World War the engine spent time in France before coming to London in 1967 and to the Ffestiniog in that same year being named Mountaineer. During 1969 she was converted from right-hand to left-hand drive. In 1972 she was converted to oil firing with superheating and piston valves added receiving a new boiler in 1983. By 2006 her boiler certificate was expired. As of 2016 she is still stored pending overhaul.