[2][3] The design was attributed to the NCC's Chief Mechanical Engineer H. P. Stewart who was with the permission of William Stanier able to draw on designs and parts from the NCC's owners, the London, Midland and Scottish Railway (LMS).
[1] They were able to reach speeds of over 80 miles per hour (130 km/h),[1] while their coal consumption was considered extremely economical.
[3] 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 Portrush taking just 80 minutes.
[2] The original plans were to name the class after Irish Chieftains, however there were concerns this might not be acceptable to some sections of the community.
[1] While none of the original class were preserved, the Railway Preservation Society of Ireland possess a spare set of driving wheels and motion for use constructing a replica, numbered 105 to continue where the original group left off.