The Peppercorn K1s proved to be useful and versatile engines. They worked extensively over ex-LNER territory but were chiefly associated with North East England, and like their K4 predecessors, the West Highland Line.
The Peppercorn K1s proved to be useful and versatile engines, operating extensively over former LNER territory, particularly in North East England, similar to their K4 predecessors on the West Highland Line.