Derek, Tom offered to send a copy on the second posting, and I could easily do likewise. Apart from which Jim has already given chapter and verse.

Jim, the song 'The Water is Wide' which you give is indeed a collection of floaters and impossible to identify in terms of one other song unless you count it as a separate song on its own in which case it is probably unique.

The 'Ripest of Apples' above does indeed commence with the floater but the other 2 verses are very close to Dominic's version of Carrickfergus and if I was classifying or applying a Roud number I would classify it as a version of Carrickfergus based on the fact that two thirds of the fragment are definitely from that song. Hybrids like this are indeed difficult to classify.

'I'm often drunk' and 'Carrickfergus', although they each have their own autonomy, have most of their verses in common. Without the benefit of a close study of all versions of both I wouldn't like to theorise on which came first. The former is very common on broadsides all over Britain, the latter from oral tradition in Ireland.