I happened to take a picture of the morning Jacobite almost exactly 46 years on in the very same location as the query image [see image 54302], passing milepost 99 and Inverlochy Primary on the approach to Fort William Junction, hauled by Black 5 45407 Lancashire Fusilier. Typical Fort William weather.
Mark Wringe [06/07/2016]

Having waited alongside the Mallaig line for a Glasgow bound Sprinter to clear the section, [See image 29132] 66099 propels four empty fuel tanks back to the Fort William Junction signal so that it can follow the passenger train south.
Mark Bartlett [18/05/2010]

Fort William signal box, July 1991.
Ian Dinmore [/07/1991]
All photographs of Fort William Junction