I take the point about revival singers being more likely to neaten up & square off tunes than the opposite, although I do think there's a bit of tendency among some singers to handle unaccompanied songs with kid gloves - delivering each line with all due respect but losing the connective bounce of the melody as a whole.

Bellamy's top end was quite something. I don't have any trouble with the octave leap in On Board A 98, but I find Soldier, Soldier an absolute killer. I've never managed the final "yea-HO" in Santa Fe Trail, either (and I've only ever heard one person hit it).