I haven’t commented on the O antiphons this year, but rather refer you to an article I wrote exactly a year ago – Beautiful Article on the O Antiphons. We begin the O antiphons on the 16th December with O Sapientia, not on the 17th like in the Roman rite, so that O Virgo virginum is sung this day on the 23rd.

It appears that northern France and southern England were doing more or less the same thing, which is hardly surprising given that Sarum is fundamentally the Use of Rouen.  Some other parts of France were no different, as attested by this setting from the late fifteenth century by Josquin des Prez (alternatively spelt des Prés, of the prairies).