As CME in post-war austerity Britain, Ivatt continued to build standard existing LMS locomotive types for which parts were readily available. Two additional LMS Princess Coronation Class 4-6-2 express locomotives were built and several modified Black Fives and the work of 'rebuilding' the Royal Scot and Patriot classes continued. The LMS Ivatt Class 4 2-6-0 was introduced as well as the notable "Mickey Mouse" LMS Ivatt Class 2 2-6-0 and LMS Ivatt Class 2 2-6-2T, built to replace life expired 19th century branch line 0-6-0 and motor train 2-4-2T locomotive types, and the Class WT 2-6-4T locomotives for the Northern Counties Committee. The famous Ivatt twins, diesel-electric locomotives numbered 10000 and 10001, built by the LMS at Derby in association with English Electric were Britain's first main-line diesel locomotives and were designed to operate singly or in pairs.