Bruce's comment above is a little misleading. Although the 17th century Carman's/Comber's Whistle are very much the same plot they have no text in common with the 18th century song here. I have 2 fairly different garland texts from mid to late 18th century, one printed in Worcester titled 'Billy and Nelly' in the Bodleian but not online (probably the older of the 2); and the other possibly printed in Scotland titled 'The Slippings of Yarn' available on the NLS website LC2890 (13). If it originated in Ireland (certainly set in Dublin) then it is possibly early 18th century. Its style is no earlier.