We have a winner.
There are actually two big clues in the picture.
The 37 is actually running into the loop on the right not the left with is the UK norm. You generally only see this on lines fitted with RETB.
The second is the top of the grain loading silo in the top left of the picture. This dominates Muir of Ord.
During this period Inverness had a number of sets of coaching stock the Green and Cream set with the former Class 101 observation saloon and a few sets in Provincial Livery which were working Kyle and West Highland because Scotrail has suffered cronic overcrowding the previous summer. Scotrail did not have any locos at the time and used to rent in Civil Engineers 37s to work the trains.
1993 saw petrolium 37 430 428 etc.
This is the period when all the sleepers were booked with generator cars and 2 x 37s. Kyle was 37 hauled no heat RAJV 37s and some FDTE 37/4s on the West Highland between FTW and MLG with an evening trip to CNR.