This is interesting.
The Antiphon is the Proper for Compline set by the editor of the New Living Parish Hymn book, John de Luca. It is a lovely little song that would be useful on it’s own in other circumstances.
The verses are based on the Canticle of Simeon from Luke 2:29-32, the Nunc Dimmitis and set to Plainsong: Mode viii.
This is just the antiphon: