A comment passed around many years ago, was that in a side to side comparison between a Deltic and a 47 for overall operating costs including overhaul, when the side by side numbers were calculated as an ownership and operating cost per hour, the figure for a 47 was lower than a Detic, but on cost per mile the Deltic figure was lower than a 47. If that is more than an urban myth, then a Deltic will prosper on long-distance high-speed intensive workings, ie the ECML, and therefore it is hard to justify cascading a Deltic to less demanding work