The Dukedog sobriquet comes from the solution, a locomotive built from the sturdy double-frame chassis of a Bulldog class 4-4-0 locomotive fitted with the lighter weight but standard type boiler and cab from a Duke class 4-4-0 engine. The result was quite out of place in the Swindon locomotive family, outside frames and boiler domes were features which had been discarded under Churchwards' management, but the dome did give the locomotives a quite distinguished look.
It was intended that the class carry the names of Earls, however the gentlemen concerned quickly took exception to their titles being carried by locomotives of such antiquated appearance and the engines ran without names.
9017 was completed at Swindon in March 1938 as 3217. The locomtoives allocation history shows a career spent on the Cambrian section, working from Aberyystwyth throughout the BR era, with a few years at Machynlleth under GWR ownership.
Note that these are the shed allocations at the begining of the year and it is likely the locomotive would have worked from many of the Cambrian route sheds during this period.
One of the last Dukedogs withdrawn in 1960, by then one of the last double framed locomotives in BR service, a fund was being raised for the preservation of an example from the class. BR helpfully kept 9017 in store at Oswestry until 1962 when funds were available to complete the purchase. 9017 must have been in good condition as it worked to Old Oak Common under it's own steam on February 1st, continuing on to Brighton for turning before being delivered to it's new home, the Bluebell Railway at Sheffield Park.
9017 has been in operation from 2004 until withdrawn recently for overhaul, working on the Bluebell and visiting several other heritage railways.
The GWRs Dukedog class was created in the 1930s in response to the need for new locomotives with a axle load lower than the Churchward designed 2-6-0 and 4-6-0 types. The standard Churchward engines were too heavy for several important secondary routes, especially the former Cambrian routes into mid-Wales, where the pre-grouping locos were becoming worn out.
In service the Dukedogs proved capable engines provided the work did not demand too much of the boiler which, being smaller than the original Bulldog boiler, had little reserve capacity. On the Cambrian section and other holiday branchlines the locomotives were often hauling express trains through to seaside destinations over routes where the heavier mainline engines which brought the trains from Paddington could not go.