Well, I never knew that. "Based his lyrics closely" is a bit of a misnomer. Most times I sing a song the way I sing it is a little different from the way I learnt it, but I wouldn't say I'd written a new song on the strength of that.

Having said that, the variations from the broadside version (see the clicky thing in the previous piosting by anon) are, I'd say, improvements. More to the point, unless I'm very much mistaken (which I may be) the tune is Pete St John's, which makes it a new song after all. But I'd sooner call it a new version.