By the way the reference for McNeil's 'My Boy Tammy' being in Herd and on broadsides in 1776. McNeil was born in 1746 so this could easily still be one of his earlier pieces.

That he based it on an older song closer to Billy Boy is indisputable. Stenhouse in his 'Illustrations of the lyric Poetry and Music of Scotland' 1853 which is in effect a concordance to Johnson's Musical Museum, gives 2 verses of the earlier piece NcNeil based it on.

Is she fit to soop the house, My boy Tammy? x2
She's just as fit to soop the house
As the cat to tak a mouse;
And yet she's but a young thing just come frae her mammy.

How auld's the bonny young thing, my boy Tammy? x2
She's twice six and twice seven,
Twice twenty and eleven
And yet she's but a young thing just come frae her mammy.