The 4-6-0 wheel arrangement that appeared in 1894, quickly became the most common locomotive for main line passenger and mixed traffic work in Britain.
A dubious asset, without which none of the younger Drummond's locomotives was complete, was the provision of a reversing gear, a troublesome mechanism if it were not well maintained.
In 1892, the opportunity was taken to purchase two 4-4-0T engines which had been built by Dübs and Company for the Uruguay Eastern Railway but not delivered due to a financial hitch.
When the Far North Line opened to Golspie in 1871, the 3rd Duke of Sutherland had purchased a small 2-4-0T from Kitson and Company for his private train.
On his succession, the 4th Duke decided to have a new locomotive built, and the original Dunrobin was sold to the Highland Railway in 1895.