The maximum tractive effort of 50,000 lbf (220 kN) was unusually high for a Type 2 locomotive but, as there were five (not four) driving axles, the risk of wheelslip was minimal.

Work had begun on the Pilot Scheme in 1954 and the first plan for 174 locomotives (all classes) had been produced by October 1954, including 20 of these Metro-Vick Type B locos, although orders were not placed until November 1955.

Crossley in Manchester had a suitable design in production as a generator set for the Admiralty and had also used it for a class of locomotives in Australia.

[5] They suffered frequent failures and by 1961 the entire class was handed back to the manufacturer for remedial work on the engines and to cure problems with cab windows falling out while running.

They were also used in pairs to cover for failures and were recorded as taking the London–Glasgow sleeper, a notoriously heavy train, forwards from Carlisle without problems.

A quotation was obtained by BR from English Electric for re-engining with an uprated version of the reliable 8SVT prime mover, already proven in the Class 20, and this was close to proceeding.

A single locomotive, D5705, survived by historical accident, being renumbered S15705 and used from December 1968 by the Research Division for its Tribology Test train.

The Class 15 Preservation Society has signed an agreement with the owners of D5705 to become its custodians during its restoration and operation for the next ten years, although funding will remain separate.