This gave a more even torque than with a 2-cylinder locomotive and reduced the risk of wheelslip under heavy load.

All four passed into London and North Eastern Railway ownership at the 1923 grouping.

At the time all four locomotives were allocated to Mexborough engine shed.

Two new locomotives (with superheaters and boosters) were built by the LNER in 1932 and classified S1/3.

All six locomotives passed into British Railways ownership in 1948 and were numbered 69900-69905.