British Rail Class 17

The BR Class 17 Clayton holds the unwanted distinction of being the shortest-lived class of main-line diesel locomotive ever built for British Railways. Of the 117 locomotives constructed between 1962 and 1965, virtually all had been withdrawn by 1971 — a service life of as little as five or six years for the later examples. The cause was not the locomotive concept itself, which was sound, but the catastrophic unreliability of the Paxman 6ZHXL prime movers that powered them, an engine that proved wholly unsuited to the continuous demands of main-line traction.

The Clayton was a Bo-Bo diesel-electric with a distinctive centre-cab layout. Each locomotive was powered by two Paxman 6ZHXL six-cylinder engines, each producing 450 hp, for a combined output of 900 hp. The diesel-electric transmission drove four nose-suspended traction motors, one per axle. The 117 locomotives were built in two batches: D8500–D8587 by Clayton Equipment Company of Hatton, Derbyshire, and D8588–D8616 by Beyer Peacock of Manchester. All were allocated to the Scottish Region and the Eastern Region.

The Paxman engines failed repeatedly from the outset. Cooling problems, bearing failures, and chronic fuel system difficulties meant that the Claytons spent far more time in the repair shops than in traffic. Withdrawal began in 1968 — just six years after the first examples were delivered — and the entire class had been retired by 1971. The rapid withdrawal of such a large and relatively new class represented a significant financial loss to British Railways.

Of 117 locomotives built, D8568 survives — both the complete locomotive at the Chinnor & Princes Risborough Railway and the cab section preserved separately at Derby Museum. It is the sole physical record of a locomotive class that, had its engines been reliable, might have given two decades of useful service.