The Great Central Railway (GCR) Class 8A was a class of 0-8-0 steam locomotive built between 1902 and 1911 for handling heavy coal trains over the Pennines. They all passed to the LNER in 1923, who redesignated them Class Q4. Between 1942 and 1943, thirteen were rebuilt as 0-8-0T locomotives and reclassified as Class Q1.
Baxter, Bertram (1988). Baxter, David, ed. British Locomotive Catalogue 1825–1923, Volume 5B: Great Northern Railway and Great Central Railway. Ashbourne, Derbyshire: Moorland Publishing Company. ISBN978-0-903485-86-9.
Boddy, M. G.; Brown, W. A.; Hennigan, W.; Hoole, Ken; Neve, E.; Yeadon, W. B. (September 1984). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 6C: Tender Engines—Classes Q1 to Y10. Kenilworth: RCTS. ISBN0-901115-55-X.