There are threads around about "Deck of Cards". I believe it was written by T. 'Texas' Tyler, and I have the Wink Martindale version (I didn't know Red 'Teddy Bear' Sovine also recorded it). I googled it a while back; but haven't lately...
Could the children have been taught at home by their parents?
One by one the poem/music could have been distributed without notice.
It seems we all need to look back into history and see if Catholics were really prosecuted during these times. That, as far as I am aware, has not been researched on this particular thread.