Like his siblings, he had little contact with his mother after his parents separated in 1811. In 1829 Augustus was appointed a Chaplain of his father (then Duke of Clarence) and later that year he was presented with the vicary of Mapledurham in Oxfordshire, succeeding John Sumner (later Bishop of Chester and Archbishop of Canterbury).
King William IV was a lavish benefactor of the church and the parish and, among his gifts was the clock in the tower which bears his initials, ″West R.″. He also made generous contributions to extend the vicarage and to enclose its adjacent grounds with substantial provisions for the foundation of a new school in the village. The marvellous collection of silver gilt communion plate presented to the church by Lord Augustus shortly after his appointment was probably in turn a gift from his father.
In 1830 he was appointed Chaplain in ordinary to his father (now King William IV), and on 24 May 1831 was granted the rank of a marquess" younger son, being appointed Chaplain to Queen Adelaide after his father’s accession to the throne in 1832.
Following his studies at Trinity College, Cambridge, he received the degrees of Bachelor of Laws (2 June 1832) and Doctor of Laws (6 July 1835). On 2 January 1845 Augustus married Sarah Elizabeth Catharine Gordon (c 1828 – 23 March 1901), daughter of Major Lord Henry Gordon (brother of the 10th Marquess of Huntly) and Louisa Payne.
They had six children:
Dorothea FitzClarence (27 October 1845 – 15 May 1870), married Thomas William Goff. Had issue. Eva FitzClarence (1 January 1847 – 2 March 1918).
Beatrice FitzClarence (1 January 1847 – d 18 March 1909), twin with Eva.
Augustus FitzClarence (13 February 1849 – 16 October 1861), died in infancy. Henry Edward FitzClarence (19 January 1853 – 19 February 1930), married Mary Isabel Templer Parsons. Had issue. Mary FitzClarence (posthumously, September 1854 – 14 March 1858), died in infancy.
