They were the last engines that were built at the company's Lochgorm works in Inverness, and were used on branch line services.
[2] All four locomotives passed to the LMS in 1923, where they were numbered 15051–15054 and given power classification '0P'.
These spent their final years based at Helmsdale for working the Dornoch Light Railway, which required locomotives with exceptionally light axle loadings.
By the time they were finally withdrawn (in 1956 and 1957 respectively) they were the last former Highland Railway locomotives still in use, and were still in almost original condition.
In order to replace these locomotives, British Railways transferred two GWR 1600 Class 0-6-0PT locomotives (numbers 1646 and 1649) to Helmsdale to work the Dornoch Light Railway.