The design of 11001 was therefore intended to be able to overcome some of these issues with its greater power of 500hp and higher speed. It should be noted, perhaps surprisingly, that its Tractive Effort at 33,000lb was the same as a Bulleid Q1.

N°11001 was completed at Ashford in 1950. Unlike the earlier 350hp diesel electric locomotives it had a totally mechanical drive comprising of a Paxman Ricardo V12 12RHP engine coupled to a two range, three speed gearbox though a Sinclair fluid coupling. Final drive was via a jackshaft. Its body styling was quite unique with a long bonnet, which unusually housed the fuel tank at the front end rather than a radiator, and a very high arc cab roof with large angled front windows. The 4' 6" wheels, in common with other Bulleid designs of the time, were of the Bulleid-Firth Brown type.

In the high-speed range it was originally intended to be able to run at a maximum speed of just below 45 mph. It turned out however to be neither a shunter nor a trip engine. The low-speed range was too inflexible for shunting, and the high-speed range, with only three gear steps, was too low for line duties. It worked from Norwood for a time, but unfortunately spent a long time out of service and was finally withdrawn in 1959.
It was originally painted in BR loco black that was later amended to green.