http://folkcasters.blogspot.com/2011/02/sticky-questions-about-folk-awards.html including these thoughts on the Mumfords conundrum

"However, the reason that the Mumfords, Noah etc haven't been nominated is not that they've simply been ignored. It's not even that they aren't folk, beyond a simplistic definition dreamed up by a journalist looking for an angle. No, the real reason is that there is a great deal of far more interesting music out there, and even that doesn't all get a look in"