The Great Western Railway 3252 or Duke Class were 4-4-0 steam locomotives with outside frames and parallel domed boilers.

[5] The first 25 tenders built also had Mansell pattern wheels, and a shorter than normal wheelbase of 11 ft (3.35 m) so that the locomotives would fit on the smaller turntables then in use west of Newton Abbot.

[7] Eighteen of the Duke class were later rebuilt with domeless tapered boilers and Belpaire fireboxes between October 1906 and January 1909.

[8] By December 1923 all remaining Dukes had been fitted with flush-topped Belpaire fireboxes and domed boilers pressed to 180 lbf/in2 (1.2 MPa).

[10] The class had distinctive long smokeboxes, extended to hold a diaphragm plate and net for spark prevention.

[14] A number of the class had been transferred to the ex-Cambrian Railways main line, where permanent way restrictions debarred the use of heavier locomotives.

3265, Tre Pol and Pen, was withdrawn, and the cylinders and motion, together with a spare Duke boiler and smokebox, were fitted to the straight-topped frames and cab of Bulldog no.

[16] The onset of World War II brought a halt to the program, the last replacement being in November 1939, leaving ten Dukes to pass into British Railways ownership.