Nearly all broad gauge locomotives built after 1846 for the GWR, and those railways it operated, were built at the GWR's works at Swindon. Daniel Gooch was locomotive superintendent from 1837 until 1864, a period which saw the broad gauge reach its zenith.
Great Western 2-2-2 - the first locomotive built at Swindon (April 1846) and was designed to show the capabilities of the broad gauge. It had 8 foot (2.46m) driving wheels and was later converted to a 4-2-2. It was withdrawn in December 1870
Prince 2-2-2 - 6 locomotives built between August 1846 and March 1847. They were smaller versions of Great Western, with 7 foot (2.15m) driving wheels. After a few years the Iron Duke class replaced them on the Exeter expresses, and the Prince class engines worked mainly on the Birmingham line. All were withdrawn in 1870.
Iron Duke 4-2-2 - 29 locomotives: 22 built at Swindon between April 1847 and March 1851 and a further 7 built by Rothwell & Co between November 1854 and July 1855. These were the premier express engines of the broad gauge, with 8 foot (2.46m) driving wheels. They were gradually withdrawn between 1871 and 1884, several being rebuilt or individually replaced by the Iron Duke Renewal (Rover) class.
Bogie 4-4-0T - 15 locomotives: 2 built at Swindon in 1849 and 13 built by R & W Hawthorn between June 1854 and March 1855. These saddle tank engines had 5 foot (1.54m) driving wheels and were designed for branch and local passenger traffic. The design was copied by the South Devon Railway for its passenger locomotives. All but one were withdrawn between 1871 and 1873. The last, Horace, was withdrawn in December 1880.
Waverley 4-4-0 - 10 locomotives built by R. Stephenson & Co between February and June 1855. They had 7 foot (2.15m) driving wheels and worked in the Bristol area and on the South Wales line. The design was not a success as an express engine and the locomotives were confined to operating passenger trains on slower, heavier graded lines. Two were withdrawn in 1872, the rest in 1876.
Victoria 2-4-0 - 18 locomotives built at Swindon in two batches - "5th lot passenger" between August and November 1856 (8 engines) and "6th lot passenger" between May 1863 and May 1864. These locomotives had 6ft 6in (2.00m) driving wheels and were essentially a smaller and more successful version of the Waverley class. Several worked on the Weymouth line. All were withdrawn between 1876 and 1881.
Metropolitan 2-4-0T - 22 engines with 6 foot (1.85m) driving wheels built between June 1862 and October 1864 to work the Metropolitan Railway in London. All were fitted with condensing apparatus. The design was not successful and the class was replaced on the Metropolitan Railway after a short while. The condensing apparatus was removed and four locomotives were converted to tender engines. The tank engines worked London suburban trains, while the tender engines worked the Salisbury branch and one at Bristol. All were withdrawn between 1871 and 1877.
Avalanche 0-6-0T - a tank engine built by Stothert and Slaughter in February 1846. It served as a banking engine at Box tunnel for many years and was withdrawn in August 1865.
Premier 0-6-0 - ("1st lot goods") - 12 locomotives built between February 1846 and May 1847. Premier was in fact the first locomotive completed at Swindon, but its boiler was made elsewhere, so is not regarded as "the first Swindon built engine". Like all subsequent broad gauge goods locomotives built between 1846 and 1864, they had 5 foot (1.54m) driving wheels. They were the last class of locomotive to be built with "haystack" fireboxes. They were withdrawn between 1866 and 1871.
Pyracmon 0-6-0 - ("2nd lot goods") - 6 locomotives built between November 1847 and July 1848. These engines were slightly larger than the Premier class and had a raised firebox that became the common design on Great Western locomotives. The locomotives were withdrawn between 1871 and 1873.
Caesar 0-6-0 - ("3rd lot goods") - 8 locomotives built between June 1851 and February 1852. Very similar to the Pyracmon class and the Standard Goods class which followed. 6 were withdrawn between 1871 and 1874, the remaining two survived until 1879 (Druid) and 1880 (Caesar).
Banking 0-6-0T - 4 saddle tank locomotives built as part of the 5th and 6th lot goods (2 each) in October 1852 and September/October 1854. One of the class, Juno, was sold to the South Devon Railway in 1872 and renamed Stromboli. It returned to GWR ownership when the South Devon Railway was absorbed in 1876, retaining its new name. These engines appear to have worked mainly on the west of England lines. The engines were withdrawn in 1871, 1881, 1883 and 1889 (Stromboli).
Standard Goods 0-6-0 (also known as the Ariadne and Caliph class) - 102 locomotives built in seven lots between May 1852 and March 1863. These engines handled the bulk of the goods traffic and were gradually withdrawn from 1871 onwards. One of the class, Europa (built in March 1853 and rebuilt with a new boiler in 1869), survived until the end of the broad gauge in May 1892.