When Peter Drummond departed to the Glasgow and South Western Railway at the end of 1911 Smith was appointed Chief Mechanical Engineer in his place.
When the effects of hammer blow were taken into account, the 'Rivers' put the same total weight onto the track as the previous 'Castle' Class 4-6-0s.
The Highland managed to sell all six locomotives to the Caledonian Railway, and legend has it that they made a profit of £500 per engine in the process.
By the 1920s, the effects of hammer blow were more widely understood, and it was accepted that the locomotives could safely work over the Highland Main Line.
In fact, taking hammer blow into account, the total weight which the 'Rivers' put onto the track was around a ton less than the 'Clan' 4-6-0s which had been built to replace them.