They were standard designs for British practice of the time, with inside cylinders and 5 ft 0 in (1.524 m) diameter driving wheels.

These had inside bearing double bogie tenders, rather like the watercart designs brother Dugald was supplying on the London and South Western Railway.

These lacked the watercart tenders but had cross water tubes in the firebox.

21 is recorded as retaining this boiler in unmodified form until 1934.

All passed into London Midland and Scottish Railway (LMS) ownership in 1923.