In Folksongs of Britain and Ireland, Peter Kennedy ties "Mare and the Foal" to "Rigs of the Time" and "The Hard Times of Old England" because they "contain verses of complaint against various tradesmen."
Of course, the more obvious connection is between these songs:

• Mare and the Foal (above)
• Soldier and the Sailor
• Parson and the Clerk
  And these in the Digital Tradition:
• MA SHEELA
• THE FIRST THING
• TOPMAN AND AFTERGUARD

All follow the same pattern, with a prayer in each verse recited by one party, and the other party answering "Amen."
-Joe-