An excellent model of the striking silver and purple liveried class 57/6 prototype locomotive, as used by Poerterbrook and First Great Western to test and prove the class 57 rebuild design with electric train supply before delivery of production locomotives. 57601 operated intensively on First Great Western, hauling daytime trains formed with air conditioned Mk2 coaches and the Night Riviera sleeper service from London to Penzance until replaced by the production FGW 57/6's.

Rebuilt for leasing company Porterbrook in conjunction with First Great Western 57601 was the prototype passenger service class 57. The specification required a high output electric train supply generator to allow sleeper trains to be warmed quickly in addition to the life extension overhaul and engine changes already proved by the Freightliner 57s. The locomotive was worked on First Great Western locomotive hauled services alongside FGWs green painted 47 fleet to prove the design. Following delivery of the production locomotives 57601 has passed into the hands of West Coast Railways for charter train operations.