Following trials with the prototype DP1 Deltic locomotive, an order was placed with English Electric for a production fleet of 22 locomotives to replace Gresley Pacific steam locomotives.
They originally arrived from the manufacturer in two-tone green; the dark BR green on top, with a narrower strip of a lighter, lime green along the bottom to disguise the shape. By 1966 they began to be painted in corporate Rail Blue with yellow ends - the first so treated was D9002; the last to be painted blue was D9014.
In the late 1970s the Deltics began to be supplanted on express services by InterCity 125s, and the Deltics were relegated to semi-fast or newspaper/parcels/sleeper services. Withdrawal came at the end of 1981. Six locomotives were preserved and some still run railtours, with 55022 even finding a new lease of life on freight duties with GB Railfreight.
For Train Simulator, Kuju Entertainment developed the Class 55 which was default content in Rail Simulator, RailWorks 2, and RailWorks 3: Train Simulator 2012. Later versions of the game require the European Loco & Asset Pack