L&YR Class 31

The Lancashire and Yorkshire Railway Class 31 was a series of superheated 0-8-0 heavy goods locomotives designed by George Hughes and built at Horwich Works from 1908, representing a significant development from Aspinall's original Class 30 0-8-0. Hughes applied superheating to the eight-coupled heavy goods configuration, giving the Class 31 substantially better thermal efficiency and performance than the saturated Class 30 on the same heavy coal and mineral duties.

The combination of eight coupled wheels for maximum adhesion and superheating for efficiency made the Class 31 one of the most effective heavy freight locomotives operating on any pre-Grouping British railway. On the L&YR's demanding mineral traffic — loaded coal trains from the Yorkshire coalfields crossing the Pennines to Lancashire, and the reverse flows of empty wagons — the Class 31's superheated performance gave it a clear advantage over the saturated predecessors.

The Class 31s passed to the LMS at the 1923 Grouping, where Hughes himself was briefly appointed CME before the appointment of Fowler. Under the LMS the Class 31s continued on heavy freight duties. None was preserved, though the class represents an important stage in the development of British heavy freight locomotive practice.