This is a Scots 'street song'. Various verses were accreted to it during the late 50s, but the original is quite venerable. The taped version from which Ewan MacColl was stated to have got the tune to make the song popular was I have been told fairly clearly in 6/8 time, and MacColl is supposed to have smoothed it out into 4/4. In his collection The Singing Island MacColl says "Originally a very beautiful pastoral song in the tempo of a slow (minor) strathspey, Johnny Lad moved to Glasgow during the late 19th C and was transformed into a children's street song. The lyric became urbanised and the original air was abandoned in favour of a catchy but much plainer tune." MacColl credits the song to his father "from the singing of William Miller of Stirling." He also refers to Ord p158 for the song, but that's an error - it should be p168 of Ord's Bothy Ballads, which has @drink the buckles off my shoon' but is otherwise the same lyric. So Ord is the oldest source I know of.