According to Allmusic.com, NORTH SEA HOLES is sung by The Corries on "Bonnet, Belt and Sword," where it is attributed to E. MacColl—and by John Doyle on "Evening Comes Early," where it is attributed to Ewan McColl (sic) and Peggy Seeger.

Also, it says NORTH SEA SHOALS/SWEET MOLLY (a medley, apparently) is performed by Ross Kennedy on "Twisted Fingers," where it is attributed to E. McCall (sic)/Traditional.

However, this Corries discography, put up by a fan, apparently, lists it as NORTH SEA SHOALS.

At Peggy Seeger's web site, there is no complete listing of songs in "The Essential Ewan MacColl Songbook," but several songs are mentioned by name in a review quoted from Dirty Linen, and NORTH SEA HOLES is one of them. There is no mention of NORTH SEA SHOALS.

It seems likely that, even if Dirty Linen had made a mistake, Peggy Seeger would have corrected it before quoting the review on her web site. Therefore, my best guess is, NORTH SEA HOLES is the original title, but the folk process has worked on it, and some people sing it as NORTH SEA SHOALS.