Hi Annraoi!The first time I ever heard An Bunnan Bui was about 22 years ago. The singer was a mandolinist from Dublin by the name of Johnny Beggan and he sang it in English. Johnny had only 3 verses. When I was getting ready to send my song collection to the publisher, I asked a couple of old friends, Roy Harris and Mick Moloney, to look over the manuscript. Mick was the one who came up with the missing verse.
In addition to the O'Sullivan book noted above, you'll find it in my folk song collection, A Bonnie Bunch of Roses (New York, Oak, 1983)- http://www.folklegacy.com/books.htm
It was also recorded in English by my friend Tim Lyons on a Leader/Trailer LP back in the 1970s. The song was certainly written in Irish but, as you can see, it has been sung in English for at least a quarter of a century.
All the best,
Dan Milner