I very much enjoyed Jamie Stone's article in the Newsletter. Others will probably have pointed out that tank engines were seen occasionally on the North Line when the Dornoch Branch engines went to the works in Inverness. In the late Fifties, these were GWR 0-6-0Ts and before that HR 0-4-4Ts.
My holiday records from Tain show 54470 and 45098 on shed each night on 29 and 30 July 1959. The Pickersgill 4-4-0 would have worked the 3pm all stations from Inverness and it would likely have been this train and this class of engine that Jamie remembers travelling home behind. These locomotives were indeed "smaller with a taller chimney" than the ubiquitous Black Fives.