When Daniel Gooch took over as Locomotive Superintendent of the Great Western Railway in 1837, the locomotives being built to Brunel's specifications were an odd assortment of engines, many of which which subsequently proved to be total failures. In addition to Brunel's "freaks", the Great Western Railway acquired two locomotives, North Star and Morning Star, that had been left on the maker's hands after the original purchaser, the New Orleans Railway (USA), had defaulted. Gooch was impressed by the performance of these two locomotives and ordered a further 10 Star class engines. He also used the basic design of the Stars for the specifications for a further 105 six wheel locomotives that became known as Gooch's "first standard design".
62 engines built by 7 makers and delivered between March 1840 and December 1842. These engines had 7 foot (2.15 metre) driving wheels and were designed for passenger traffic. The original design has 15" x 18" cylinders and a "gothic" (or "haystack") style firebox. The cylinders were later replaced with 16" x 20" cylinders to improve performance.
14 of the class were rebuilt in the early 1860s with slightly longer frames and a round top firebox (see picture). The unaltered locomotives were withdrawn in the late 1860s, partly because they were too small for the heavier traffic loads, and partly because several broad gauge lines had been converted to standard gauge. The rebuilt engines worked until the mid 1870s, and the last, "Ixion", was withdrawn in July 1879. In later years, the class became known as the "Priam" class.
21 engines built by 3 makers and delivered between April 1840 and January 1842. These were smaller versions of the Fire Fly class with 6 foot (1.85 metre) driving wheels. They were intended to operate passenger trains between Swindon, Bristol and Exeter, but were found to lack adhesive weight. To remedy this they were all converted to saddle tanks in 1849 and 1850, in which form they ran until they ceased work between 1864 and 1879.
18 engines built by 3 makers and delivered between January 1841 and July 1842. They had 5 foot (1.54 metre) coupled driving wheels and were the first purpose built goods locomotives on the GWR. Like the Sun class, they were found to lack adhesive weight, so were converted to saddle tanks in 1849/50. Most were withdrawn in 1870, although 4 survived until 1874.
4 engines built by Nasmyth Gaskell and Co and delivered between July and October 1842. They had 5 foot (1.54 metre) coupled driving wheels and were otherwise identical in design to the Fire Fly class. Their primary function was goods traffic and "Goliah" worked on the South Devon Railway for a number of years. All four engines were withdrawn between July 1870 and June 1871.
No further locomotives were built for the GWR until 1846, when the locomotive works at Swindon opened.