The design featured a boiler pressed to 150 lbf/in2 (1.03 MPa) delivering saturated steam to two 18 by 24 in (457 by 610 mm) cylinders connected by Joy valve gear to the driving wheels.

[3] They were a tank engine version of the LNWR Cauliflower Class, built from 1892.

They were built as mixed traffic locomotives, and were frequently used on suburban services.

By the time of the 1923 Grouping, 77 were still in service and passed to the London, Midland and Scottish Railway who gave them power classification 1P, and renumbered them 6860 to 6939.

Fifteen were still in service at nationalisation in 1948, but only two survived to receive their British Railways' number.