Check Mudcat thread 9604. A post there by Grant Cockburn gives the lyrics; Rita McNeil, in her spoken introduction to the song: "This song is dedicated to my father, Dan McFee, who worked in the coal mines of Cape Breton."
Aggie could be Rita or a relative.

George should be able to answer this.

It is a hard one to google because there are a number of songs with 'working man' in the title. I was trying to find a copyright or original publisher. Not sure what another post in thread 9604 refers to- something about a BBC single released by Fruher and the date 1987.

9604: Working Man