Looking at leaves and cuttings recently at the V&A Museum I looked again at one I had not seen in person for more than a decade:
The large initial includes fairly distinctive decoration and a human face:
The letter was mentioned in the 1923 catalogue:
here, where the cutting is attributed to the Middle Rhine, c.1460, perhaps on account of the fact that the Master of the Playing Cards is associated with Mainz through the decoration of the Giant Bible of Mainz and at least one copy of the Gutenberg Bible.
In case it is of any help, here are two other leaves from the same manuscript, also at the V&A:
Can anyone explain the significance of the initial "e" between the stag's antlers?