The Highland Railway began as the Inverness and Nairn Railway (later the Inverness and Aberdeen Junction Railway), which operated the other lines which became part of the Highland Railway on its formation in 1865. The first locomotive superintendent was William Barclay, who was a nephew of Alexander Allan. The locomotives supplied initially were classic Allan designs, small 2-2-2s and 2-4-0s, outside cylindered and with external framing and (initially at least) not even a weatherboard to protect the engine men. It was later decided that a cab was essential to protect them from winter weather.

The first locomotives were two 2-2-2s were supplied by Hawthorns and Company of Leith in 1855, and a second pair delivered in 1857. Cylinder dimensions were 15 by 20 inches (381 by 508 mm), and driving wheel diameters were 6 feet 0 inches (1,829 mm). The boiler pressure was originally 100 psi (6.9 bar; 690 kPa), later being revised to 120 psi (8.3 bar; 830 kPa).

The model of No 1 Raigmore is by H Clyne and was shown at a Harrogate exhibition.