That's her above, with stigmata and crown of thorns, nuzzling up against Christ's body. This is not the St Catherine who died on a wheel, but the medieval mystic and passionate letter-writer who underwent a 'mystical marriage' with Christ, in which, for want of a ring, Christ placed his own foreskin on Catherine's finger. Nothing odd about that then.

Our painting was described by Mary Kisler as 'the oddest little devotional painting' and it has long been filed under 'artist unknown'. That remains the case, but a source has just come to light. If we flip the image thus:

Then we clearly have a source in a fresco by Francesco Vanni (1563-1610) in the sanctuary of St Catherine in Siena:

As luck would have it, Vanni's work is reproduced on the cover of a modern edition of the life of St Catherine by Thomas of Siena (known as Il Caffarini) and thus easily located using nothing more than Google images.

Exactly how, when, why, or by whom our copy was made remains a mystery.