Louisanna was in fact the first cousin of William's first wife with Eliza having been the third daughter of John Bird Sumner.

From his father's second marriage Arthur was the eldest son, having four older sisters, Ella Sophia (1838–1928); Emily Louisa (1840–1887); Ada Frances (1841–1893); and Edith Harriet (1842–1922).

At Arthur's baptism his sponsors were his grandfather, Charles Richard Sumner and his grandmother, Jennie as well as his maternal uncle, Robert.

[8] They had three children: Hugh Sumner (1844–1942), who later served in the Indian Forest Service; Percy (Peter) Lemprière (1886–1950) who became a surgeon in the Royal Navy; and Edith Monica (1890–1954) who became a renowned butterfly expert.

On the floor of the church, near to the choir stalls, is a tablet of Cumberland stone in memory of Arthur Sumner Gibson.

Arthur's youngest brother, Alan George Sumner Gibson became the Coadjutor Bishop of Cape Town.