The first two diesel-electric locomotives soon known as class D16/2 were ordered in 1947 by the Southern Railway, but only delivered in 1950 to British Railways where they were numbered 10201 and 10202. They were designed by Bulleid and, like Ivatt's D16/1, had a V16 engine from English Electric that delivered 1,750 hp in this case. Their chassis consisted of two bogies with a flexible leading axle and three powered axles each. Their gear ratio was set for a top speed of 110 mph or 177 km/h.
Both were tested in service in the Southern Region and a third one was built in 1954 that received the number 10203. This had an optimized version of the engine that delivered 2,000 hp. Its gear ratio had been changed for a top speed of 90 mph or 145 km/h and a higher tractive effort. In 1955 all three came to the London Midland Region and were compared with the D16/1. Their successor was the class 40 whose outside appearance was designed by English Electric. But on the inside, it used the same engine and running gear design as the 10203. The prototype locomotives were withdrawn in 1963 due to being non-standard.
