I should have said above that the "original" tune appears to be "Never Love Thee More"--here's the abc file for anyone else's comparisons/feedback...
Cheers.
Mary
X: 45
T:Never Love Thee More
M:6/8
L:1/8
B:The Round Band Book of Playford
K:G
E | "G"D>ED "Am7"G2A | "G"B>cB "C"A2G | "G"dB2 "C"A2G
| "Am"E3 "D7"E2E | "G"D>ED "Em"G2A | "G"B>cB "C6"A2G
| "G"dB2 "C"c2d | "C"e3 e2e | "G"dB2 "C"A2G
| "Am7"c2d "C"e>dc | "G"dBc A2G | "Am"E3 "D7"E2E
| "G"D>ED G>AG | "G7"Bcd "C"e>dc | "G"dBc "C7"A2G | "G"G3 G2 ||