GWR 3206 Class

They underwent various alterations during their working lives, such as thicker tyres giving slightly larger wheels, the gradual adoption of cylinders with a 26 in (660 mm) stroke, and larger diameter boilers of various sorts, as was usual at this period. Between 1910 and 1915, some of the class received taller chimneys resembling those of the Dean Singles.

The Barnums were "express mixed traffic engines" and to start with worked from Swindon to Gloucester and South Wales, and to Weymouth. A few subsequently went to the Northern Division, but in the early 20th century most were at Bristol, Oxford, Swindon and Westbury. By the 1920s they were reduced to branch-line work, apart from a brief spell on the Cambrian main line, and all were withdrawn by early 1937.^[2]

• 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.
• Tabor, F.J. (February 1956). White, D.E. (ed.). The Locomotives of the Great Western Railway, part four: Six-wheeled Tender Engines. Kenilworth: RCTS.