I can't get that site to do any more than download a whole bunch of widget clutter. The link isn't a direct one to an mp3 as it looks like.

So I just have this comment to go on:

" The singer is asking his love to do the impossible, and then come back to him and ask for his hand."

Which suggests that it's derivative from the sentimentalized Carthy/S&G version. Look at most of the versions given here - the Cambric Shirt one in particular - and it comes across as a ferocious rejection: she can have me back when hell freezes over. (In its original form the tune Sharp found for it, which is probably where the Carthy/S&G one started out, reinforces that tone of cold fury - dogged equal notes most of the way through). It's as dark as anything in blues or rap.

I'm not really interested in hearing yet another rendition that turns it into sugary slop.