"If anything, it sounded fairly neutral with a very soft hint of Derbyshire vowels to me."

Yep, spot on IMHO.

I don't get this hatred of the 'phoney accent' bit - there are plenty of other singers around who sing in accents other than their own natural one, yet they're held as near-deities in the bright Firmament of Folkiedom. Example - listen to Martin Simpson's accent in the songs he sings which have their roots in the American South - not a hint of Scunny there, but plenty of 'phoney American'! Absolutely NOT a criticism of Martin's delivery, for the very good reason that, because of the origin and language of these songs, to sing them with a Lincolnshire, or for that matter, Derbyshire, or Fackin' Landon accent would be ridiculous.

Jack sings and writes great songs which are of a certain, American-influenced style, and he sings them in an accent which owes much to his own Derbyshire roots, but which is gently and sympathetically adjusted to make it suitable for the style and lyrics of the songs. WTF's wrong with that?

JMHO! :-)