The first batch (later LNER Class D26) was designed by Matthew Holmes in 1902 and had 6-foot-6-inch (1.981 m) driving wheels for express passenger work.

Three more batches (later LNER Classes D32, D33, and D34) were designed by William P. Reid with 6-foot-0-inch (1.829 m) driving wheels for mixed traffic work.

It was common practice for the North British Railway to assign similar engines to the same class group, whereas the LNER system allowed only identical engines to bear the same class designation.

Twelve engines ordered in March 1902 and built at Cowlairs railway works in 1903.

In May 1959, the two cameramen of Railway Roundabout, Patrick Whitehouse and John Adams, visited the West Highland Line in Mallaig, and arranged a filming special taking place on a double-headed train from Glasgow Queen Street to Fort William.

The filming special had taken place over several days and used three runs of the trip in the process.

The first trip saw a Southern Railway luggage van behind the engine hauling the train, Glen Falloch, and many lineside shots were possible.