was the lowest number of a locomotive in that class, and an alpha-numerical which used a letter to indicate the wheel arrangement, and a number, with the lowest number given to the most powerful class with that wheel arrangement. The latter system was only used by Inchicore Works for accounting purposes, while the former was used by locomotive crews and the drawing office at Inchicore Works. Note that narrow gauge locomotive classes included the letter N after the prefix letter, letter C was also used for Bo-Bo diesels, and that letters B, C, D, F, J, and K were used for the same wheel arrangements by the London and North Eastern Railway, while E and G changed places. In 1945, the GSR became part of Córas Iompair Éireann (CIÉ), which amalgamated the railway, road transport and canal functions of the State. CIÉ was nationalised in 1950 and settled on a policy of replacing steam with diesel locomotives, a process that was completed in 1962. Midland Great Western Railway (1847–1924) M. Atock (1872–1901) MGWR Class D – GSR Class 530 or Class D16 MGWR Class E – GSR Class 551 or Class J26 MGWR Class H – GSR Class 619 or Class J6 MGWR Class K – GSR Class 650 or Class G2 MGWR Classes L and Lm – GSR Classes 573 and 594, Classes J18 and J19 MGWR Class Ln – GSR Class 563 or Class J16 MGWR Class P – GSR Class 614 or Class J10 MGWR Class W – GSR Class 234 or Class J17 E. Cusack (1901–1915) MGWR Classes A, As and A1 – GSR class 545 or Class D5 MGWR Class B – GSR Class 646 or Class J2 MGWR Classes C and Cs – GSR Class 536 or Class D7 MGWR Classes C and C1 – GSR Class 540 or Class D6 W. H. Morton (1915–1924) MGWR Classes F, Fa, and Fb – GSR Class 623 or Class J5 Great Southern and Western Railway (1845–1924) Alexander McDonnell (1864–1883) GS&WR Class 2 – GSR Class 2 or Class D19 GS&WR Class 21 – GSR Class 21 or Class G4 GS&WR Class 47 – GSR Class 47 or Class E3 GS&WR Class 90 – GSR Class 90 or Class J30 GS&WR Class 91 – GSR Class 91 or Class J29 GS&WR Class 92 – GSR Class 92 or Class H2 GS&WR Class 101 – GSR Class 101