[1] A requirement was expressed by the BTC at a meeting on 15 January 1960 for new Type 4 designs of Co-Co arrangement, which would be lighter than the earlier 1Co-Co1 locomotives such as the Peak classes, produced under the Pilot Scheme.

While not in any sense a failure, the design was the victim of advances in locomotive technology (specifically, the power obtainable from single medium-speed diesel engines) and was never duplicated.

Returning to British Railways in 1963, Falcon spent six months working out of Darnall shed, Sheffield, on passenger and freight trains, after which its testing was completed.

Advances in diesel engine technology made it obsolete almost from the beginning, with the development of larger and comparatively lightweight single powerplants.

[10] Falcon was first allocated to Bristol Bath Road again working alongside Class 52s, and by March 1974 to Ebbw Junction,[11][12] for use on iron ore trains.

In 1975, the locomotive was deemed uneconomic to operate due to its non-standard status and, despite efforts to preserve it, Falcon was broken up in March–April 1976 at Cashmore's of Newport.