DP2 was a success because it didn't have all the electronic crud crammed into the class 50's. I think BR may have had a hand in the addition of the 'embrionic brain' to the class 50 design. At the time the class 50's were coming into service, BR had also rebuilt 10 class 71's as class 74's, which were also packed full of solid state electronic control equipment. Even though it was unsucessful at the time, it paved the way for the modern computer controlled traction equipment that does work (most of the time).