|Fresco by Johann Georg Unruhe - Courtesy of Wikipedia|
O Fathers of Our Ancient Faith is written by the Benedictine Nuns of Stanbrook Abbey. In the Divine Office (1974) it is sung at Morning Prayer in the Common of Apostles. It is set to the anonymous tune associated with the 7th century Latin hymn: Creator Alme Siderum, as featured in the following video.
Tune: Creator Alme Siderum