 Many Irish branch lines, some very long, were lightly laid and needed special locomotives to work the trains.With a locomotive weight just of and maximum axle load of just over , the GS&WR Class 2 was a most successful type fulfilling these requirements.This class of 4-4-0 locomotives was designed by Alexander McDonnell, the Locomotive Superintendent of the GS&WR, and built between 1877 and 1880.