GWR 1813 Class

Between 1894 and 1906 all but two (nos. 1817/53) of the 1813s were rebuilt with saddle tanks, and between 1903 and 1906, five were rebuilt with either short or full-length pannier tanks, resulting in a very early example of this type of engine. All but one (no. 1829) of the rest were so converted between 1911 and 1927, as had become standard practice on the Great Western.^[4]

The class also carried an unusually wide variety of different boilers. With one exception (no. 1817) all of the original domeless boilers were replaced by domed boilers with round-top fireboxes between 1894 and 1902, and these were of two principal types: most had their domes on the front half of the boiler barrel, but some had the dome on the rear half of the barrel. Several locomotives were fitted with both types at different times.^[4]

No. 1817 had its domeless boiler replaced by a domed boiler having a Belpaire firebox in 1904, and from 1905 onwards, all but two (nos. 1825/9) of the others had their domed round-top boilers replaced by domed Belpaire boilers. Although the round-top type continued to be fitted, there were no reversions from Belpaire to round-top. As with the round-top boilers, the dome could be either on the front half or the rear half of the boiler barrel, but only nos. 1816/43 had the dome at the front, and both were subsequently given replacement boilers having domes on the rear half. The last conversion from round-top to Belpaire occurred in 1927.^[4]

Beginning in 1915, thirty of the locomotives were provided with superheaters, in several cases this occurred when the locomotive was also rebuilt from round-top to Belpaire. All of the superheated boilers had Belpaire fireboxes with the dome mounted on the rear half of the boiler barrel. Just over half of the superheater conversions subsequently reverted to using saturated steam.^[5]

Withdrawal commenced in May 1928. Most of the class were withdrawn over the next eleven years, leaving six (nos. 1823/31/5/8/46/7) still in service at the outbreak of World War II. Five of these were withdrawn between 1944 and 1947, leaving one (No. 1835) which alone passed into British Railways stock, to be withdrawn in January 1949.^[6]

• Allcock, N. J.; Davies, F. K.; le Fleming, H. M.; Maskelyne, J. N.; Reed, P. J. T.; Tabor, F. J. (1968) [1951]. White, D. E. (ed.). The Locomotives of the Great Western Railway, part one: Preliminary Survey. Kenilworth: RCTS.
• le Fleming, H. M. (April 1958). White, D. E. (ed.). The Locomotives of the Great Western Railway, part five: Six-coupled Tank Engines. RCTS. ISBN 0-901115-35-5. OCLC 500544510. {{cite book}}: ISBN / Date incompatibility (help)