5051 Earl Bathurst at Toddington during the 2006 Centenary gala (Photograph: Steve George)  


5043 Barbury Castle carrying the Cheltenham Flyer headboard (Photograph: courtesy STEAM: Museum of the Great Western Railway picture library)  


An unidentified Castle class loco with the Cheltenham Flyer (Photograph: courtesy STEAM: Museum of the Great Western Railway picture library)  

The 4079 or Castle class 4-6-0s was arguably the most successful express locomotive design ever to run in the UK.  A development of Churchward's excellent four-cylinder Star class 4-6-0s, C B Collett improved the design in several respects - but particularly a brand new boiler (Swindon No. 8) and larger cylinders.  The first was introduced in 1924 and boasted a significantly higher tractive effort than its predecessor class and, indeed, greater power than the new Gresley 'Pacifics' on the Great Northern (later London & North Eastern Railway).  For their power, the locomotives were amongst the most economical in the country and, with their graceful lines set off by copper-capped chimney and brass safety valve bonnet the GWR publicity machine made much of them.  The 'Castles' quickly made their mark with the heaviest West of England expresses while they were regular motive power for the Cheltenham Spa Express, or 'Cheltenham Flyer', which was justifiably touted as the 'fastest train in the world'. 

The 'Flyer' was initially scheduled to cover the 77 mile leg of the journey from Swindon to Paddington in 75 minutes in 1923, an average speed of 62mph.  However, inter-company rivalry gradually led to progressive increases in this start-to-stop timing, until in June 1932 the train, with no. 5006 Tregenna Castle in charge, covered the distance in 56 minutes - an average speed of 81.6mph.  This involved sustained running over much of the journey well in excess of 90mph. 

After the Second World War, Collett's successor, F W Hawksworth, introduced minor improvements to the design, such as double blast pipes and larger superheaters - which served to enhance their already-impressive performance and members of the class started to clock the occasional 100mph.  Production continued until 1948, the class eventually numbering 171 locomotives.  Of those, 15 were rebuilds of the Star class and one was a rebuild of the Great Western's only 'Pacific', no. 111 'The Great Bear'.  That engine became no. 7037 and was named simply 'Swindon' 

The locomotive on display is no. 5051 'Earl Bathurst', one of just eight members of the class to survive.  It was completed in May 1936 and initially carried the name 'Drysllwyn Castle', taking the name 'Earl Bathurst' in 1937, from a 3200 or 'Dukedog' class 4-4-0.  This happened after objections from the peers concerned who didn't like their names on humble 4-4-0's that worked a long way from London!  5051 was withdrawn from British Railways service after covering more than 1.3 million miles and consigned to Barry scrapyard in South Wales.  It was purchased by the Great Western Society in 1969, being the fourth locomotive to leave the yeard and was delivered by rail to the Society's Didcot base.  5051 has since performed admirably on the main line and, indeed, visited the Honeybourne Line in 2006. 

The locomotive is currently 'out of ticket' (ie, its boiler certificate has expired) and is awaiting overhaul.  The locomotive is displayed by kind permission of Didcot Railway Centre.