I got my copy of Bone, Antler, Ivory and Horn in the mail yesterday! Flipping to the section on bone flutes, I found...
I have an ILL out on some of Graeme Lawson's reports on Anglo-Saxon bone flute finds. No offense to Arthur MacGregor, but if there's only two such bone flutes cited in his book, I may as well check them out in the original archaeological reports and see what the musicologist has to say about them. Then I go back to the bone book to figure out how to make the thing.