The British Rail Class 51 "Super Deltic" was a proposed diesel locomotive design for British Rail and it was meant to be built by English-Electric.
Plans for the Design[]
The British Rail Class 51 "Super Deltic" was going to resemble the design of the chassis from the Class 50 but the body shell was be modified 2 meters longer compared to the original body shell of the Class 50.
Why Wasn't it Built?[]
The reasons to why the British Rail Class 51 "Super Deltic" never got off the ground/was never built at all, was because British Rail was busy trying to deal with all the government stuff, they also were trying to be more ambitious, plus they were also busy with innovating and investing money into a well-known project, the Advanced Passenger Train (or the APT) which had barely ever worked, but British Rail did wind up with the Class 43 HST, which was very good for its lifetime.