The long version sung by Pearl Webb that you have just posted looks quite similar to the one recorded from Ethel Findlater in Orkney - including the stanza where captain proposes to leave the murderer on an island if he confesses (as in Jeff Stockton's version too, but unlike the 18th century broadside text) and a number of other details.
There are three recordings of Ethel Findlater singing the ballad on different occasions on the Tobar an Dualchais website. The clearest is http://www.tobarandualchais.co.uk/en/fullrecord/64318/3 from 1969, but in the other two she also gives some information about how she got the text of the ballad in a manuscript book from a friend, and the tune from her mother-in-law.