Caswall was the son of Ro­bert Clarke Cas­wall, Vi­car of Yate­ley. He at­tend­ed Chig­well Gram­mar School, Marl­bo­rough School, and Brase­nose Coll­ege, Ox­ford, where he grad­u­at­ed with hon­ors. Be­fore leav­ing Ox­ford, he pub­lished, un­der the pseu­do­nym of Scrib­ler­us Red­i­vi­vus, “The Art of Pluck,” in imi­ta­tion of Aris­to­tle, a sa­tire on the ways of the care­less col­lege stu­dent.

In 1838, Caswall was or­dained as a dea­con, and 1839 as an An­gli­can priest. In 1840 he be­came per­pe­tu­al cur­ate at Strat­ford-sub-Cas­tle near Sal­is­bury. By 1847, though, he had switched to Ro­man Ca­thol­i­cism and went to the Or­a­tory of St. Phil­ip Ne­ri at Edg­bas­ton, where he did most of his hymn work. Cas­wall is best re­mem­bered as a trans­lat­or of an­cient hymns, though he al­so wrote orig­in­al ly­rics. His works in­clude:

• Sermons on the Seen and the Un­seen, 1846
• Lyra Ca­thol­i­ca, 1849
• The Masque of Ma­ry, and Other Po­ems, 1858
• The Ca­tho­lic’s La­tin In­struct­or in the Prin­ci­pal Church Of­fic­es and De­vo­tions