An additional twenty locomotives, featuring slight design modifications, were produced under the direction of George Hughes for the LMS between 1925 and 1926.

Although initially classified as passenger locomotives by the LMS, they were frequently deployed on goods trains later in their service life.

This shift in usage earned them the nickname Greybacks, likely referencing their long, grimy boilers.

Alternatively, the nickname may have been an insult coined by former Glasgow and South Western Railway enginemen, as "greyback" was an old term for a louse.

[1] Withdrawals from service began in 1944, but twenty-three locomotives remained operational when British Railways was formed in 1948.