Highland Railway O Class
The Highland Railway O Class were 4-4-0 tank engines. Three were put into service sometime between 1873 and 1892.
They were all out of service by 1918.
No other details seem to be available, nor has it been possible to track down any positively identified photographs.
One phototograph exists of a service on the Burghead branch which could well portray a Class O example. While not very clear it shows a small tank engine with classic Jones front end appearance, an enclosed Stroudley-like cab, and an extended bunker. If the sweep of plating from the smokebox to cylinders can not be seen it would be very easy to mistake it for one of the Stroudley LBSCR designs. The caption identifies the locomotive as No 58 'Burghead'.
No 52 (built 1893) is believed to be of this class.