The type proved chronically unreliable in Eastern Region service - by March 1960 the Hornsey allocation had moved to New England Yard, Peterborough for storage.

This came to the attention of the newspapers and the Daily Telegraph reported that brand new diesel locomotives were being hidden and dumped, which caused questions to be asked in Parliament.

They were joined on the Scottish Region by the first 38 locos, which were allocated to Glasgow Eastfield depot, close to the North British factory at Springburn where they had been built.

Common double headers included Oban & Callander workings, Glasgow-Dundee/Aberdeen expresses, and many freights, and the Ballater Royal train was entrusted to two locos with a standby.

The positioning of minor components within the locomotive bodyshell meant that small faults could only be rectified on depot or by return to a railway workshop, which resulted in poor daily availability for traffic figures for the type.

Most were cut up by Scottish scrap dealers McWilliams of Shettleston or Barnes and Bell of Coatbridge, but locomotive D6122 was sold to Woodham Brothers scrapyard in Barry, Vale of Glamorgan, South Wales, after a re-railing demonstration at Hither Green, Southern Region on 2 November 1967 where it languished until 1980 before being broken up.