Confirmation!

 A S Stephen's House priest who was a student there in the time of Canon Arthur Couratin writes: "I was there for these very distinctive features of the Vigil rite in Arthur's time, so they cannot possibly have been composed later. The style is utterly Arthurian both in structure and in the pithy turn of phrase, and it never occurred to anyone at the House that they might have been the product of anyone other than the Principal."

Thank you, Father! I have accordingly removed the question marks in my headings!!