Kate Rusby uses an alternate guitar tuning, Double Dropped D (DADGBD) on her beatiful song, Who Will Sing Me Lullabies. 

When I performed the song in SATB from with CSI:Halifax Community Choir I accompanied the pianist on guitar but in standard tuning. I didn't like the sound and promised myself that I would learn the DAGGBD version someday.
So recently I did this arrangement in Musescore Studio help develop skills.  I varied the tempo, added drums and Bass guitar and represented vocals using Sax. 
The Drums, Bass, Sax and Piano in this cover are digitally created using Musescore 4. I play the guitar and my vocals are multi-take recorded.