LMS 1831

LMS No. 1831 was a prototype diesel-electric shunting locomotive built by the London Midland and Scottish Railway at Derby Works in 1932, one of the earliest diesel shunter prototypes to be evaluated by a British main-line railway and a significant step in the LMS's investigation of diesel traction for yard and trip working. The locomotive used an English Electric diesel engine and electric transmission, establishing the basic formula — diesel engine driving a DC generator to power axle-hung traction motors — that would eventually become the standard for British diesel shunters in the BR era.

The LMS was among the most progressive of the Big Four companies in exploring diesel traction in the 1930s, and H. G. Ivatt's predecessor at Derby, William Stanier (CME from 1932), supported the investigation of diesel shunting as a replacement for the numerous 0-6-0 tank engines that occupied the LMS's extensive marshalling yards. No. 1831 was an early result of this interest, a single prototype that evaluated the diesel-electric concept in practical yard shunting service before the more standardised diesel shunter designs of the later 1930s.

No. 1831 was a one-off prototype and was not replicated directly, but the operational experience it provided informed the subsequent development of LMS and later BR diesel shunter practice. It was not preserved.