I did the Edale Skyline recently, 21 miles, well prob more given the navigation difficulties. Most of the time in cloud with my glasses fogged up, cold, wet often up to my knees in bog, a fair bit of ascent.
4 hours 40 mins
Great race, felt far better at the end than after my marathons, recommend it highly.
I guess this is fell running by the above definitions.
Roger
P.S I'm a psychiatrist so I know I'm not mad, personality disordered is another matter.