Oiel Verrey--a corruption of ' Oie Feaill Voirrey,' the eve of the Feast of Mary or Christmas Eve - however often rendered as Ilvary.
The Manx custom was for the parishioners to remain in the church after the service and for individual members of the congregation to sing carvals or carols (few of which had any Christmas or Marian connection).
The most quoted description of this custom is that by William Kennish who describes that which took place in Maughold in the 1830s - however Hugh Stowell Brown provides a more critical account of such a service in Kirk Braddan in the 1830s. There is an earlier description of drunken behaviour at Ballaugh in 1758.
It was on the evening of Christmas Day, and it bore the name of Ill-vary; I do not know how to spell the word; it is Manx, and I believe has reference to the Virgin Mary. The service concluded with one or two Christmas carols, sung by some rustics who had got them up for the occasion. What those in Manx were I cannot tell; but I remember one in English in which the singers spoke of Mary in such horrible fashion that my father could bear it no longer; he stood up in the reading-desk, angrily rebuked them for their abominable indecency, and brought the service to a hasty close. Such was Kirk Braddan when my father went to it in 1832, and such, or worse, were almost all the parish churches in the Island.
Interestingly Train writing of the 1830/40s though mentioning the decoration does not confirm Kennish's details.
Leech in his guide of 1861 portrays it as a conventional Christmas eve service .