Iron Duke (3)

The prototype locomotive, Great Western, was built as a 2-2-2 locomotive in April 1846, but was soon converted to a 4-2-2 arrangement. The remainder of the class entered service between April 1847 and July 1855.
Locomotives of the Iron Duke class were extremely fast and had an estimated top speed of about 80 mph (133 km/h). They were used to haul the Flying Dutchman express train which, for several decades, was the world's fastest train. In 1852 the daily service from London Paddington Station to Exeter (194 miles) was achieved with an average speed of 53 mph (88 km/h); with the flatter section between London and Swindon covered at an average speed of 59 mph [1].
From about 1865, the Iron Duke Class was known as the Alma Class.
In May to July 1870, three locomotives (Great Britain, Prometheus and Estaffete) were extensively rebuilt with new frames and boilers, but retaining their original names. Following these, further locomotives were built to similar specifications, entering service between August 1871 and July 1888. These new locomotives are generally referred to as the Rover class. Although these locomotives took the names of withdrawn locomotives of the original design, they were not rebuilt from them like the first three, but entirely new locomotives (though it is believed that Rover, Swallow and Balaklava may have included some parts from the earlier locomotives of those names).