A tremendous advance in the express locomotive practice of the LMSR was made in 1927 by the introduction of the three-cylinder 4-6-0 "Royal Scot" engines. The 'Royal Scot' Class was designed at Derby under the direction of Henry Fowler, with much help from the Southern Railway and the North British Locomotive Company, who built the first fifty. The 'Royal Scot' locomotives were introduced to eliminate as far as possible, the then frequent double-heading up shap, they were very successful engines, though always rough riders. Three cylinders were provided with three sets of Walschearts gear, and the slightly tapered boiler was 5'9" maximum diameter. As built, theyhad vacuum pumps driven from the L.H. cross-head, and brakes to the bogie wheels. the smaller 3,500 gallon Midland tender was fitted to the class from new. Later, another 20 engines to the same design were constructed at the Derby works of the LMSR. The smoke deflector plates were not originally fitted. The Pioneer Locomotive 'Royal Scot' 6100 had a successful visit to America and canada in 1933. many detail improvements were made to this engine, and ultimately to all the class by W.A.Stanier, among them the provision of 4,000 gallon tenders. The final metamorphosis of the 'Royal Scot' began in 1943 when No.6103 was extensively rebuilt with re-designed cylinders and valves, and with a tapered boiler, double blast pipes and double chimney. The original cab however, was retained. All of the seventy 'Royal Scots' were ultimately rebuilt and became one of the finest large 4-6-0 locomotives ever known.