This may or may not be relevant, but looking at Michael's post the BG chorus starts with 'To me' or sometimes 'With me' and the way The Watersons sing BH 'With me'. I know this is a common way to start these nonsense choruses, especially in shanties but it may be relevant. For instance, did BH at some point, or a variant of it, have a chorus....' With me tow row row, tow row row, fol de etc.? And then some local wag in Boston thought he'd make the line more appropriate to Boston or have more meaning. Just a thought.