Certainly very influential on the modern revival, but 'most significant'? Over a span of nearly 400 years, I very much doubt it. It's largely irrelevant to this particular discussion in any case; as a modern collation it can tell us nothing about the history of the song.

To answer a few points made a little earlier in this recently revived thread:

Charlie:

Let's give that folklorist his proper name: Barre Toelken. It's a matter of record that Baez was, shall we say, rather less than frank about where she got some of her early material. Anything of hers should only be considered authentic, and useful for the purposes of discussion, if it can be traced to a traditional source. That particular text isn't in Bronson, but plenty of oral examples have turned up since than. It would be interesting to know more about the provenance of this one. It wouldn't be at all surprising to find that she got it from Toelken and 'forgot' (see Sandy Paton's comments in earlier discussions here on songs that she learned from him and later pretended to have had from 'little old men in Ireland' or some such).

'Big Vern':

England has never been a 'Calvinist' country. The 1658 printing (Child 81A) has:

Little Musgrave came to the church-dore
The preist was at private masse
But he had more minde of the faire women
Then he had of our lady['s] grace.

1658 was the year Cromwell died. Although Catholicism was widely frowned upon (in much the same way that Communism, for example, has been in America in more recent times) a reference to 'our lady' clearly was not considered odd or inappropriate at that time. In fact, the ballad sheet issued by Henry Gosson (Child 81C) was around 20 years earlier, perhaps more, and makes no reference to 'our lady' at all. There is probably no future in trying to guess the age of the song by that means.

Similarly, King Henry appears only in late (collected in the 20th century) American versions; so there is no help to be had there, as was pointed out when this discussion was originally started in 2005.

We can say only that the song was known around 1611; as I said a few years back in this very thread, it was probably quite new at that time.