Given this long history, it is not surprising that as principles of harmony were incorporated into western musical practice, a system of harmonized chant should arise for the singing of psalmody. Anglican chant is such a system, originating around the time of Orlando Gibbons (1583-1625). Its use was limited to cathedrals and collegiate choral foundations until the 19th century, when with the Oxford Movement, many practices that were once the preserve of cathedrals found their way into parish churches.
Anglican chant uses a single (usually chant-like) harmonized melodic line which is repeated as many times as is necessary to carry the psalm. The text is "pointed", meaning that certain portions of the text are to be sustained on a single note ("recitation"), and specific syllables are designated to carry the melodic line forward ("inflection"). Anglican chant is usually heard with an organ accompaniment, and this has become an art form in itself, requiring great skill on the part of the organist in terms of registration (selection of organ stops), dynamics and articulation.
The chant heard in today's liturgy is the work of Sir Edward Bairstow (1874-1946), and is one of the most enduring chant melodies in the repertoire, most of which arose during the 19th century as Anglican chant became more widely known and practiced.
Today's anthem represents a musical rendering of a psalm in a style very different from Anglican chant. The music is an early composition by Franz Schubert (1797-1828), and was originally conceived as a song. As with all Schubert's songs, the accompaniment is integral to the overall composition, and does much to set the mood of the piece. The Lord is my Shepherd is an arrangement of Schubert's composition by Sir John Stainer (1840-1901), with the text of Psalm 23 substituting for the original German text of the song. Stainer was organist of Christ Church Cathedral in Oxford and professor of music at the university. He was knighted in 1888 by Queen Victoria for his musical endeavors.