" 
 : I have a theory regarding those odd mileage intervals. 
 ::Before the railway was opened, the company would have prepared a prospectus, and in that, gave approximate positions for the stations as: first station four miles from Hull; second and subsequent stations every three miles after that (7 miles, 10, 13 etc. to 28 miles). They then chose the real station sites to be more conveniently situated as regards settlements and existing roads.  When Whishaw was compiling his book, he was unable to get the exact final distances, so he used the approximate distances from the prospectus, but for some reason subtracted them all from 30.65 to give distances from Selby instead of Hull, hence 0, 2.65, 8.65, 11.65 etc. On that basis, there is a gap at 5.65 miles from Selby (25 miles from Hull), which corresponds to Wressle - whose present-day distance is 24 mi 79 ch from Hull Paragon according to Trackmaps. 
 :I don't know if that's a true explanation or not, but it seems to fit.   "