Tried to search for the lyrics online without any luck. The family story goes like this: my great aunt learned the song from a record she purchased probably in the 1940s, and sung and played it incessantly, until it infected the whole family. A couple generations later, all that's left is a memory of the first few lines:

Just seven more days, dear
Until I pass on
From the awful old scaffold
To the silence beyond.

Needless to say, it's about a condemned criminal writing or speaking to his wife/girlfriend/mother.