After the “Livingston Thompson” was the last original Ffestiniog Double Fairlie to be retired due to wear and tear in 1971, continuing to run the railway with this type of locomotive was an option. Since rebuilding the locomotive would have required too much effort, the decision was made to completely build a new locomotive. This was one of the first times in history that a heritage railway had a steam locomotive built from scratch. Today there are several examples that follow the same pattern.

Since the locomotive, christened the “Earl of Merioneth”, had to complete everyday service on the tourist line, it was built with a few differences compared to its historical predecessors. The biggest difference was the significantly larger supplies, which should allow use without many intermediate stops. Oil was used as fuel to reduce the risk of forest fires due to sparks. Despite using refurbished bogies from older locomotives, it was able to haul trains with twelve cars and 500 passengers on a gradient of 1 in 80.

After many years in service, it was converted to coal-firing to reduce costs in view of the increased oil price. The chimneys had to be fitted with spark arrestors to further reduce the risk of fire. When the boiler deadline threatened to expire in 2018, the decision was the same as in the 1970s. This time, too, the decision was made to let the deadline expire and to build a new locomotive with the name “James Spooner”. Today the “Earl of Merioneth” is on display in Boston Lodge.