rich--true, the condemned man doesn't dwell on the mechanics of his coming death or on his possible afterlife, or on any remorse he might have for his crime--but the song's structure, message, and imagery are a bit more complex, I think, than you give it credit for: we first see the condemned man as human, connected to his family and his girlfriend, dreaming about returning to the innocent pleasures of his youth (the oak tree, the walk with Mary), yet aware of the changes time brings--the paint on the old house is now cracked and worn, and the greeting is perhaps one he received on an earlier return home. On first hearing, the first two verses are simple nostalgia for family and home and sweetheart. But when the third verse comes, the condemned man awakes surrounded by the cold grey walls, thinking of the walk to the gallows and his return home, not to be greeted but mourned, the tree of his childhood now his burial site, the green, green grass no longer a symbol of home and youth, but a grave covering.

Anyway, that's the way I try to sing it (avoiding all memory of Tom Jones' overblown version). --seed