Highland Railway class F “Duke”

David Jones had ten 4-4-0 express locomotives built by Dübs in 1874, which were first called the Bruce class and later renamed the Duke class when another class with that name was introduced. Between 1876 and 1888 the Highland Railway built seven more at their own Lochgorm workshops in Inverness.

The appearance of the locomotives was characterized by the outside frames in which the outside cylinders were arranged at an angle in the same way as, for example, Jones' later "Skye Bogies". The chimney was louvred at the front, which was intended to improve the draft in the boiler. The machines from Inverness had a slightly smaller boiler, which had a higher pressure of 150 instead of 140 psi. 

In the new class scheme that Drummond introduced in 1901, they became class F. The Dübs machines were the first to be retired from 1907 because they were the oldest. Five survived until 1923, but no longer received an LMS number.