Hard to know which of the old threads to put this one in, but I thought it ought to be recorded somewhere. I know the Urban Myth about the Catechism origin of the 12 Days song has been thoroughly debunked but here's the British Library entry for the first known printed version.

Title: Mirth without Mischief. Containing the Twelve Days of Christmas; The play of the Gaping-Wide-Mouthed-Wadling-Frog; Love and Hatred; the Art of talking with the fingers; and Nimble-Ned's alphabet and figures.

Publisher/year: London, [1780?]
Physical descr. 24º.
Added Entry: MIRTH main entry
holdings(1):All items
Holdings(BL): Ch.780/110. Request
Control number: 002507986 002649112

I'm hoping to have a look at "The play of the Gaping-Wide-Mouthed-Wadling-Frog" when I get a chance.

:-)