re Greg's "Has the current owner of the MS any rights in the tune?"

None whatsoever; the ms itself shows that the tune has been 'there' at least 200+ years, so the possibility that the composer has died less than 70 years ago, is zero.

The rest of the matter is a bit ambiguous of course, but I strongly doubt that - at least in EU - the owner would have any copyright in the ms either; it is, as a piece of art and product of genius, comparable with a painting (eg), and when the cr in it has expired, there's no getting it back.

After publishing, a new object of copyright is at hand, and other rules apply.

AKS