In reply to kathrync:
Some suggestions; I suspect some will already be in your father's library, so do check.
John Martyn's an obvious choice. If Solid Air isn't in your father's collection already, this will fit right in. Jethro Tull's Heavy Horses or Song From The Wood would both fit in too, as would pretty much anything by Richard Thompson; I suggest Mirror Blue .
A little more modern (only 20 years or so old), Beth Orton's first album, Trailer Park, meets your requirements. Grinderman's self-titled first album does too; these cover your folky and rocky bases quite well. There's an album called The Book Of Invasions by a group called The Horslips which is well worth getting to know too; again, this would pretty much fit straight in to your dad's library but it's not so well known these days so may not be there already (the rest of their output doesn't live up to the standard set by this so is best avoided). Avalanche by Thea Gilmore would work, as would an album titled This Rhythm Is Mine by Sally Barker - though this might be difficult to find.
If something more folky is needed, try Skulk by Jim Moray. This varies from the standard folk/rock Steeleye Span sound through to tunes with backgrounds that vary from northern European jazz to progressive rock mellotron washes, as well as a banjo-led cover of Fleetwood Mac's Big Love. It's better than that makes it sound!
Though it doesn't immediately fit your criteria, something by Public Service Broadcasting - try The War Room - might work, as might something by Rodrigo y Gabriella - try Live In Manchester and Dublin.
If there's space for something with a more American slant, try Rites Of Passage by the Indigo Girls; there's a terrible cover of Romeo and Juliet on there; I just skip past that and recommend everyone else does too. The rest of it varies from good to excellent.
And my completely out of left field choice for you is Ghostpoet's latest album, Dark Days + Canapes. Yes, it's modern and no, it won't immediately appeal but tell your Dad to give it time; the good stuff takes a while to sink in.
And a suggestion from even further out is the Hackney Colliery Band's Live album. Again, it'll take a while to click but click it eventually will.
Hope that helps!
T.
Edit - just noticed your 'released in the last five years' point. Well, some of my suggestions have been...
Post edited at 15:49