GWR 7 ft Priam Class

The GWR 7 ft Priam Class was a series of single-driver 2-2-2 express locomotives designed for the Great Western Railway around 1860, based on or developed from Daniel Gooch's earlier broad-gauge express types with 7 ft driving wheels. The Priam Class — named after the legendary King of Troy, following the GWR's practice of naming its broad-gauge express locomotives after figures from classical antiquity and mythology — represented the continued development of the broad-gauge single-driver express type in the period between Gooch's celebrated Iron Duke class of 1847 and the final development of broad-gauge express practice before the gauge conversion.

The broad-gauge single-driver express locomotive was a specifically GWR type: the 7 ft 0¼ in gauge allowed 7 ft driving wheels of a diameter impossible on standard gauge without raising the boiler to an impractical height, and Gooch's broad-gauge singles exploited this advantage to give the GWR's broad-gauge expresses a speed advantage over standard-gauge contemporaries that lasted until the introduction of the Stirling Singles on the GNR in 1870. The Priam Class extended this tradition with the enlarged 7 ft driving wheel that gave excellent high-speed performance on the relatively level main line between Paddington and Bristol.

The Priam Class broad-gauge singles were withdrawn as the GWR progressively converted to standard gauge, and the final elimination of broad gauge in May 1892 ended the era of the broad-gauge single-driver. None was preserved; the broad-gauge express heritage is represented by the replica Iron Duke at the STEAM Museum, Swindon.