Just stumbled on this thread as I don't visit Mudcat all that often these days.....

I am doing to sing King Offeo at a local singaound in Lewes this evening and explain how John Stickle, who is a distant relative of mine came to sing it to Patrick Shouldham Shaw's tape recorder at Baltasound in Unst in the mid-1950s. Patrick explained this to me when I met him in 1969.
I sing the four verses that John Sickle sang then and augment them with the more complete version that I found in The Oxford Book Of Ballads. I only have the student version and it does not give the sources of the versions that it prints but I believe that OBB version comes from another distant Shetland relative, Dorothy Anderson.