Caswall's poem is subscripted "O gloriosa domina", which is itself a Marian hymn, and his poem obviously is a reworking of that hymn to praise St. Ann. It does not use the first verse of the poem as a refrain.
Was there a suggested tune? I might lean toward Land of Rest for its sweetness.
To participate in the discussions on Catholic church music, sign in or register as a forum member, The forum is a project of the Church Music Association of America.