The North British Railway (NBR) West Highland line to Mallaig via Fort William presented many operating problems due to its steep gradients and severe curves, combined with very restrictive axle loading limits.

An early proposal was to use the new K3s to provide extra power, but they would have been restricted from the Mallaig section of the line, and was vetoed completely by the Civil Engineer after K3 bridge tests were made.

After nationalisation more powerful engines found their way to Fort William and 61994 was moved down to Eastfield where it was to spend most of its BR career.

both have seen major action around the North West of England allocated to Crewe hauling charter trains.

It is now placed in a museum in Fife, Scotland, built by and dedicated to its current owner, John Cameron, along with his other engine, LNER A4 Pacific no 60009 Union of South Africa.