Forty-three were built, of which thirty-five (ten D29s and twenty-five D30s) survived into British Railways ownership in 1948.

The J Class had 6' 6" driving wheels for express passenger work and a large tender which carried sufficient water to allow passenger trains to run non-stop between Edinburgh and Carlisle.

Some of the names were later re-used on LNER Peppercorn Class A1 locomotives.

New LNER numbers were allotted in 1943 in the order of construction, but the locos were not renumbered until 1946, by which time two had been withdrawn.

British Railways increased the LNER 1946 numbers by 60000 between 1948 and 1950, but some were withdrawn before this could be carried out.