I see Scroggs getting a little aroused here and no wonder. The en-route supps have it well documented from accurate surveys etc. Folklore seems to have got the better of some of the others.
Another interesting point is the lose use of the term 'miles'. In flying speak - certainly at the professional level, we mean nautical miles (6080 feet) rather than road type statute miles (5280 feet). So its not surprising that distances can become rather arbitrary.
Scroggs' 9,800 ft at Elvington, for instance, could become 1.86 statute miles which, if taken as NMs would be 11,308 ft .... etc.
Whoops, putting coloured pens down now - sorry.