In the late 1970s, the Deltics began to be supplanted by the next generation of express trains, the High Speed Train (HST), and the Deltics began to take on secondary roles. British Rail at this time had a general policy of not maintaining small non-standard fleets of locomotives, and thus the class had a limited future. When the HST fleet took over on the main East Coast services it was never likely to be economic to maintain a small non-standard class of locomotive for secondary services. Thought was given to redeploying all or some of the fleet on the Midland Main Line, the Trans-Pennine route between Newcastle and Liverpool, or the North East – South West cross-country route, but this was ultimately abandoned as uneconomic, due to maintenance and crew training costs, and the end of the decade saw the first withdrawals from service. 55 001 "St. Paddy", 55 004 "Queen's Own Highlander" and 55 020 "Nimbus" had all been out of traffic for the best part of two years and cannibalised for spares at Doncaster Works. It was decided that 55 001 and 55 020 were too heavily cannibalised to justify resurrection and they were condemned in January 1980. 55 004 was returned to service.