Interesting point Richard. Yes, John sings it the way his dad did, as do I.

When I was learning it (more than 40 years ago?!), that placing of words bothered me too, as I'd always been told it was bad form to end a line with a preposition and one should sing a whole phrase.
I experimented with moving the words round, and I might occasionally do so now, but I find that "the mountain streams where the moorcocks crow" is a complete phrase in itself and works best as the final, complete, repeated line of each verse.

I suppose I love the song as Paddy Tunney "moulded" it (as in the quote from John above).

Each to his/her own though :)