For express trains on more hilly main lines, such as Devon and Cornwall, William Dean envisaged 4-4-0 locomotives with a driving wheel diameter of five feet and eight inches. Based on his Duke class, he built No. 3312 “Bulldog” in 1898 with a larger boiler. Like the Duke, it had outside frames which had recesses in the area of the cranks of the coupling rods. The new boiler also had a steam dome, but caught the eye with a raised Belpaire firebox. 

The boiler was designed by George Jackson Churchward, who still was Dean's assistant at the time. The boiler was to become the GWR's standard boiler No. 2 and initially had the same diameter from back to front. In October 1899, No. 3352 “Camel” was completed, which is considered the first production example of the Bulldog class. With it, the boiler no longer had a steam dome and tapered from the back to the front.

Multiple batches were built in the following years, which showed some differences among them. Some still had a parallel boiler and others had a tapered boiler of varying design. Soon, the tapered boiler prevailed, as well as straight outside frames. Although the locomotives were initially referred to as the Camel class due to the first production engine, the prototype's name "Bulldog" soon caught on.

By 1909, 141 Bulldog-class members had been built, 20 of which had been rebuilt from existing Duke-class locomotives. In 1909 and 1910, another 15 of a slightly modified design, known as the Bird class, were built. It differed from the Bulldog class mainly in higher outside frames, a new bogie and a longer smokebox.

All locomotives of the two classes were retrofitted with a superheater between 1910 and 1914. Since the 4-4-0 locomotives of the GWR were initially provided with different number ranges across the classes, they were renumbered in 1912. The locomotives of the Bulldog and Bird classes received the number range between 3300 and 3455 without gaps. In August 1929, the first one of the Bulldog class was withdrawn, but the withdrawals in larger numbers did not take place until 1934 and the last one survived until 1951. From of the Bird class, the first one only disappeared in 1948, but the last one also in 1951.