The four pre grouping companies all experimented with diesel-powered shunters. By the time the BR Modernisation Report was published in 1955 there were only seven mainline diesel locomotives in operation with the first of the projected pilot scheme locomotives not entering service until 1957. Then, fourteen types of types were ordered from six independent manufacturers and two BR Works with an initial order tolling 174 locomotives. It was intended that these pilot scheme locomotives would undergo evaluation trials, but orders were increased rapidly, resulting in locomotives of varying reliability, which only became apparent after they had entered service. This photographic book reveals the progression of diesel power from shunting locomotives, ex GWR railcars and the early mainline diesels to the British railways pilot scheme successes and failures.