Natasha, you may need to open Mudcat in two or three windows simultaneously to cross-check some of these refererences.

Here's a splendid example of a song evolving into lots of different forms, discussed on Mudcat with a good many useful references: Origins: Shepherd Lad.
The thread includes the sanitised version printed in Baring Gould & Sharp's Folk Songs for Schools and notes that it's 'an insipid departure from Child ballad 112'.

Some related threads are referenced at the top of the Shepherd Lad thread. They don't include a further variation of the song, which uses the same tune and a similar chorus, but is now about whaling: The Eclipse. This gave rise in its turn to an American version which I can't recall - I will try to find it.

Valmai (Lewes)