Don, Koen,
I find myself in the peculiar position of agreeing with two people who differ from each other and neither of whom necessarily agrees with me.
Of course I've always said the origin of the imagery was Hellenistic. But not eeveryone in the Hellenistic world or even in the Greek-speaking world was a Greek.
Given that the Hellenistic period ends about 30 BC, the imagery, at least, had to be maintained in some form, somewhere until the Vms was made.
I don't think much of it arrived into the view of Latin Europeans before the mid-12thC -though I've always excepted the antecedents of the centres in the month-roundels, which could have been known to Latins by the 10thC.
Mid-12thC to c.1400 is still a fair gap, and manuscripts circulated pretty easily throughout the Latin speaking world, just as through the Islamic or Byzantine. So though I think our present manuscript made in italy, I'd be open to its having been made in England, chiefly becausethe earliest appraisals, both professional and expert-amateur found nothing to object to in that provenance.
Sometimes a hostile witness is the best witness, especially by what they cannot say. Lynn Thorndike seems to have had a strong personal antipathy towards Wilfrid, and hated alll the 'hype' about supposed Baconian authorship. He was certainly a specialist in medieval manuscripts .. and I'm sure if he could have said "this is no English manuscript" he would have jumped at the chance to demolish Wilfrid and the 'Bacon' story at one go. But he never did - nothing about the manuscript's vellum or hand obviously denied it. For myself, I'm positively inclined to arguments about England before 1400 - for the precedents, not the current MS.