On introduction the Class W
2-6-0 'Moguls' took over the principal main line expresses of the NCC. They were able to reach speeds of over , while their coal consumption was considered extremely economical. The class was the motive power for the
North Atlantic Express introduced in 1934 with the opening of the
Greenisland Loop Line and the fastest services to taking just 80 minutes. In 1937 the North Atlantic Express was scheduled from to at an average speed of making it the fastest schedule in Ireland; that time was reduced by a further minute in 1938 to achieve a scheduled start to stop. The class remained on former NCC lines until the introduction of diesel railcars on services to in 1958, after which some were transferred to other lines including cross border trains to and occasional excursions to Dublin. The final six locomotives were withdrawn in 1965. ==Livery and naming==