Hawksworth design outside cylinder engines. Breaking with the traditional GWR design path the 15xx series shows design influences from the USTAC S100 'USA Tank' engines used by the GWR during WW2. Generally similar to the 94xx pannier tanks the 15xx series featured outside cylinders and motion with 10 engines ordered by the Great Western, though not constructed until after nationalisation. Following withdraw from British Railways service three were used by the NCB at Coventry, allowing one example to survive into preservation.
Engineering prototype expected spring 2022