They were the first 4-4-0s to be introduced by the GNR, and Ivatt's first original design for the railway as well.

4351–4360) were built with a raised running plate above the coupling rods to match the Small Atlantics that were being introduced at this time.

Another duty for the class was light express passenger trains.

In 1912, Nigel Gresley replaced Ivatt as chief mechanical engineer for the GNR.

In this form, it became part of the LNER D2 Class, which had seventy other previous locomotives built between 1898 and 1909.

In the 1930s, the Stainmore Route in County Durham, which ran from Darlington to Penrith, was in need of more locomotives to replace the LNER D23 Class 4-4-0s.

Initially LNER J21 Class engines had been tried, but these tended to have motion failures, particularly after descending the line's banks due to a habit drivers had when it came to driving the class in these areas.

To do so, they were fitted with larger cabs and side windows for better crew protection.

4075 was fitted with a Thompson cab and, after World War II, was painted in LNER apple green, the only member of her class to carry this livery.