[1] When the North British railway required more dock shunting tank locomotives in 1904, rather than order further copies of the railway's standard G class (LNER class Y9) 0-4-0ST, William P. Reid introduced a completely new 0-6-0T locomotive design.

[2] The class had a 3-foot-10-inch (1.17 m) diameter, 10-foot-5-inch (3.18 m) long boiler producing 130 pounds-force per square inch (0.90 MPa) saturated steam to two outside 17-by-24-inch (432 mm × 610 mm) cylinders, which were connected to the 3-foot-9-inch (1.143 m) driving wheels by inside Stephenson valve gear actuating slide valves.

[3] All thirty five locomotives were built at the NBR's Cowlairs Works in five batches between 1904 and 1919.

[2] They were used on docks and harbours on both the east and west coasts of Scotland.

[5] At the grouping in 1923, they all passed to the London and North Eastern Railway, who classified them as class J88.