It's Muirland Meg, a version of which can be found in Burns' Merry Muses of Caledonia.
This is the one MacColl sang on the album of the same name.
Jim Carroll

17. . MUIRLAND MEG (Tune: Saw Ye My Eppie McNab)

Only a handful of Merry Muses texts have come down to us in Burns' own handwriting. "Muirland Meg" is one of these, and the present text is probably one collected by Burns' from tradition.
"Muirland Meg" is instructed to be sung to the tune "Saw Te My Eppie McNab", the title song of which is also to be found in MMC '59, p. 97. This latter song was undoubtedly the origin of Burns' song of the same title (Dick, Songs, p. 114). The tune has been traced back to 1742, but Dick believes that "From its construction it is much older than the earliest date named" (Dick, Songs, p. 394).
The present text was learned from MMC '59, p. 60 (originally from a holograph text in Burns' handwriting, but incorporating the chorus with which it appeared in MMC 1800). The tune was learned from SMM, #336.

1.        Amang oor young lassies there's Muirland Meg,
        She'll beg or she work, and she'll play or she beg,
        At thirteen her maidenheid flew to the gate,
        And the door o' her cage stands open yet.

        And for a sheep-cloot she'll do't, she'll do't,
        And for a sheep-cloot she'll do't;
        And for a toop-horn she'll do't tae the morn,
        And merrily turn and do't, and do't.

2.        Her kittle black een they wad thirl ye through,
        Her rose-bud lips cry, kiss me noo;
        The curls and links o' her bonnie black hair,
        Wad put ye in mind that the lassie has mair.
        And for a sheep-cloot etc.

3.        An armfu' o' love is her bosom sae plump,
        A span o' delight is her middle sae jimp;
        A taper, white leg, and a thumpin' thie,
        And a fiddle near by, an' ye play a wee!
        And for a sheep-cloot etc.

4.        Love's her delight, and kissin's her treasure;
        She'll stick at nae price, and ye gie her gude measure,
        As lang's a sheep-fit, and as girt's a goose-egg,
        And that's the measure o' Muirland Meg.