|Fresco by Luca Rossetti da Orta - Courtesy of Wikipedia|
Father Most Holy, Gracious and Forgiving was written by Monsignor Ronald A. Knox (1888 - 1957). In the Divine Office (1974) it is sung at Morning Prayer on Trinity Sunday. The Divine Office recommends the tune: Theophila, for it's musical setting. An alternative tune that can also be used is Christe Sanctorum, as featured in the following video.
Alternative Tune: Christe Sanctorum