Early on it was determined that the locomotive was not suited to heavy freight trains, and they quickly acquired a reputation for unreliability largely due to the engines, which continued to deliver poor performance even after extensive modifications.

The Class 17 proved to be one of the least successful of the Type 1s, such that by 1967, long lines of unserviceable locomotives could be found stored in less accessible sidings at various locations across the Central Belt of Scotland (e.g. Ardrossan and Millerhill).

[3]: 59 Production of locomotives D8500–D8587 was performed in-house by Clayton between September 1962 and February 1965, with subcontractor Beyer, Peacock and Company of Manchester delivering D8588–D8616 between March 1964 and April 1965.

[1] The Class 17 locomotive incorporated several features that were relatively novel amongst its contemporaries; to achieve the desired visibility from a single cab, it was decided to place it in a central position and use relatively low engine bays.

According to the manufacturer, the increased maintenance costs of two engines over a single unit was a worthwhile trade-off for the improved visibility made possible by such an arrangement.

The motor armatures were highly balanced to reduce vibration levels; further features included for operational convenience and safety were a relay-based automatic wheelslip detection system, which reduced power without driver intervention, and an automated fire-suppression system that discharged bottled carbon dioxide into the applicable engine bay if excessive temperatures were detected.

The cab itself was largely built out of steel, with the space between the interior and exterior surfaces lined with fibreglass and other materials for both soundproofing and heating purposes.

[1] These were carried on an underframe which was entirely composed of welded steel and featured full-length deep-section longitudinal beams, having been designed to withstand buffing forces of up to 200 tons.

In September 1963 numbers D8501 and D8536 moved to the Tyne Dock area where they were tested in multiple on Consett iron ore trains.

[5] Subsequently, all of the locomotives allocated to the Eastern Region were transferred to Haymarket where they were employed on freight traffic in southern Scotland and northern England.

[citation needed] This design was arguably the least successful diesel locomotive ever employed on British Railways, even more so than the ill-fated Metrovick Co-Bo.

The twin Paxman engines were unreliable, being prone to camshaft and cylinder head problems amongst others;[3]: 58  overall availability was around 60%, even after extensive modifications.

Forward visibility, which had dictated the whole design of the type, was not as good as had been hoped, the long noses meaning that the crew could not see the area immediately in front of the locomotive.