1958 BR details:
BR Nos; 3100-90, 4100-79, 5100-99, 6100-69, 8100-09.
Location; Most parts of the former G.W.R. system.
Origin; G.W.R. Introduced; 1906. Designer(s); Churchward and Collett.
Driving Wheel; 5 ft 8 in. Pony Wheel; 3 ft. 2 in. Trailing wheel; 3ft. 8 in.
Weight; 78 tons 9 cwt. Length; 41 ft.
Boiler Pressure; 220 lbs. sq. in. 61XX and Nos. 3100-04 225 lbs. sq. in.
Cylinders; [2] 18 in. x 30 in. Tractive Effort; 24,300 lb. 61XX 27,340lb.
Coal; 4 tons. Water; 2,000 gals.
Classification; 4-MT.

Notes: Excellent representatives of excellent Swindon general-purpose design, these locomotives evolved from a type developed from 1903 GWR No. 99, first known as the 3100 and 3150 class.
The latter were rebuilt by Collett and re-numbered in the 5100 series and new locomotives were built to this design. Ten of the 3100 series were rebuilt and re-numbered as 81XX.
In 1931 the 5100 series was continued with increased boiler pressure, being the 6100 class.
Several of the original 1906 3150 engines rebuilt as 51XX were withdrawn in the late 1940s even while new engines were being built at Swindon under BR auspices in the 41XX series. No. 5157 was built at Swindon in 1930 and worked in the Newton Abbot-Taunton area until withdrawal during the summer of 1958.