Introit for the fourth Sunday of Advent, sung by Jerycho
And while we've got the lads here, this is the only recording I know of the troped Gloria Spiritus et alme, in honour of the blessed Virgin. Spiritus et alme was the sole trope to be found in the ordo missae of the Missale Nidrosiense.
And here is an Alleluia egregie - but not the one found in the office of St Magnus: different text, different tone. Nevertheless fabulous.