The Locomotives of the Midland Railway, followed its small engine policy. The policy was later adopted by the London, Midland and Scottish Railway, and contrasted with the London and North Western Railway's policy. The small engine policy was partly the consequence of a difference in the background of senior managers. In most railway companies, the elite position was the design, construction and maintenance of locomotives. Bigger engines brought more prestige and allowed longer trains. In the Midland, the marketing department was paramount. They recognised that people wanted more frequent, shorter trains rather than an infrequent service. It concentrated on very light, very fast and frequent trains.

The London, Midland and Scottish Railway (LMS) was a British railway company. It was formed on 1 January 1923 under the Railways Act 1921, which required the grouping of over 120 separate railways into four. The companies merged into the LMS included the London and North Western Railway, the Midland Railway, the Lancashire and Yorkshire Railway, several Scottish railway companies, and numerous other, smaller ventures.