It entered London, Midland and Scottish Railway service in 1923 and the LMS renumbered it 14010 and gave it the power classification 1P.

The locomotive was withdrawn in 1935, by which time it was the last single-wheeled express engine running in Britain, and set aside for preservation.

The engine was a one-off design intended to represent both the railway and the builder at the International Exhibition of Industry, Science and Art held in Edinburgh rather than to fulfill any specific need for such a locomotive by the Caledonian.

[citation needed] Drummond and the Caledonian also co-operated with another major Scottish locomotive builder, Dübs and Company, to produce a second engine for the same Exhibition.

Such a system would overcome the 'single' type's primary drawback of starting heavy trains from a standstill while retaining its ability to cover long distances at high speeds.

123 and the Caledonian engine's strong performance coupled to the invention of Holt's steam sanding gear (which was more useful to the majority of British railway companies that used vacuum brakes rather than the Westinghouse system) led to a revival in the use of the 'single' for express passenger work in the late 19th century.

123 became nationally famous during the Race to the North of August 1888 when the companies on the east- and west-coast main lines between London and Edinburgh competed to have the fastest times.

123 was also used consistently throughout the month of the Races, being used on the fast northbound express every day for four weeks, which also proved the locomotive's reliability.

It entered London, Midland and Scottish Railway service in 1923 and the LMS renumbered it 14010 and gave it the power classification 1P.

The locomotive was withdrawn in 1935, by which time it was the last single-wheeled express engine running in Britain, and set aside for preservation.