The song came about when I got invited by my good friends Charles Kelly and Dave Haywood from Lady A to write a song together with hopes of getting it cut by specific singer songwriter we had in mind.
However, once the song was finished I liked it so much that I made them promise not to give it to anyone else. I took it too the band to see what they thought and in the end we decided it was exactly what our record needed. The rest is history!
It makes sense if you know that Will is talking about the frets irrelevant to the capo. So, when he says 6th fret, it's 4th fret with the capo on. (Basically what he means at the beginning by speaking of it in the key of A instead of G.) Hope that helps!