[3] Many of the class were fitted with superheaters from 1914 onwards, but the process was not completed – the maximum number with superheated boilers was 70.

[5] The class was designed to haul heavy coal trains from the South Yorkshire Coalfield westwards to Manchester and Liverpool, and eastwards to the ports at Grimsby and Immingham; until 1911 they also worked southwards to the marshalling yards at Woodford Halse.

For this purpose, they were allocated to the locomotive depots at Annesley, Gorton, Grimsby, Keadby, Mexborough, Sheffield and Staveley.

After the Lancashire, Derbyshire and East Coast Railway (LDECR) amalgamated with the GCR in 1907, some were sent to the former LD&ECR depots at Langwith and Tuxford.

Between 1942 and 1945, 13 locomotives were rebuilt by Edward Thompson to 0-8-0T and reclassified Class Q1; in 1943, after four had been dealt with, the LNER renumbering scheme was prepared.