Regular readers will know that I have been trying to trace leaves from a late 15th-century Book of Hours with unusual initials "MdM" and "AdM" in some of the margins (see here, here, and here).
One that has so far eluded me was reproduced in Maggs Bros., Catalogue 437: Books of Art and Allied Subjects (1923), no. 1159 plate LXI (of which a detail is shown above):