For a discussion of ABERYSTWYTH see PHH 18.

The tune's musical contour is a fine match for this text. It climbs from its initial minor phrases through a touch of major to a convincing high point in the final line before settling to a solemn close. Sing in parts throughout at a restrained pace to permit all the eighth notes to sound clearly. ABERYSTWYTH is set in the key of D at 18, which also provides a canonic harmonization that could be used effectively on stanza 2.

--Psalter Hymnal Handbook