The 'Princess Coronation' Class, to give it its correct name, was Stanier's second Pacific locomotive development and owed much to the 'Princess Royal' Class he had introduced four years earlier. They were all built at Crewe, initially as streamlined locomotives. Without the streamlined cladding, they looked fairly like the 'Princess Royals', especially without smoke deflectors which were added to the unclad 'Princess Coronations'.

The third batch, consisting of five locomotives and built in 1938, was built without streamlining and batches 6-9 built between 1944 and 1948 were likewise built from scratch without the cladding. In their case, they were built with double chimneys and the rest were converted to double chimneys as they passed through the works. The removal of streamlining from clad members of the class started in 1946 with the last being modified in 1949. This was 46243 City of Lancaster which was the only streamlined LMS loco to carry 'British Railways' on its tender; it was in wartime black. Removal of cladding left locomotives with a rounded top to the smokebox which gradually disappeared with subsequent modifications. Gradually replaced by diesels, the last member of the class to be withdrawn went in 1964 but three members of the class have been preserved. The one in the National Collection, 6229 Duchess of Hamilton, has been rebuilt to streamlined form. Interestingly, this was the locomotive which went to tour America in 1939, in the guise of 6220 Coronation and could not return until 1943.

The class were all named, either after female members of the Royal Family, not already used by the 'Princess Royal' Class, or after British cities. The former gave the class its shorter name - 'Duchess'.

Generally thought to have been the ultimate in LMS passenger locomotive development, the 'Duchess' has, since the late 1930s, been a popular subject to model, Bassett-Lowke and Trix produced streamlined versions of the 'Princess Coronation' before the Second World War and in 1939 Bassett-Lowke released their non-streamlined model. This was a subject tooled for the Hornby Dublo range but production of it had to wait until the end of hostilities. This model disappeared with the end of Dublo production in 1964 but was given a new lease of life by G&R Wrenn from 1969. The modern Hornby company produced their first version of the non-streamlined locomotive in 1977, replacing it with a retooled super-detailed model in 2002. In the last ten years, 24 versions of it have been produced.

In 2010, City of Sheffield became the first proprietary steam outline model to be fitted with a sound chip and the third one of the class to receive this is 6232 Duchess of Montrose, seen here. It was one of the five locomotives built in 1938 without streamlining. The model is in LMS Crimson Lake livery and shows the locomotive in that very early form before smoke deflectors were fitted.