The Hymn of Thanksgiving was not, of course, sung from the top of Magdalen Tower this coronaviric morning. But it was sung electronically on the Internet, quod videte. A written account of May Morning is in Dorothy Sayers, Gaudy Night, Chapter XI.
In Magdalen Chapel, there is glass from the 1630s; one of the lights shows our Lady, labelled as Deipara ... the Latin equivalent, of course, of Theotokos. I wonder if it is pure coincidence that in the May Hymn (text and music seventeenth century) there is the stanza
Tibi, aeterne Spiritus
cuius afflatu peperit
infantem Deum Maria,
It was in that interesting decade that the baroque 'salomonic' porch was built onto the University Church, with the crowned statue of the Mother of God which so infuriated the Puritans. In the late 1630s, Oriel (associated with the University Church) acquired a statue of our Lady; removed in 1650, she returned after the Restoration. S John Henry Newman (himself of Oriel) remarked "The presence of Catholicism was at length simply removed ... It took a long time to do this thoroughly; much time, much thought, much labour, much expense; but at last it was done. ... Truth was disposed of and shovelled away ..." Yet 1630s Oxford does at least slip a hesitant footnote into that summary.