Randolph Mainwaring was born in 1839 (1) at Newcastle under Lyme, England the eighth son of Rear Admiral Rowland Mainwaring (1783–1862), by his third wife Laura Maria Julia Walbergha the only child of Florian Chevillard, one of Napoleon's colonels.
He married on 15 August 1883 at Mitcham, Surrey to Edith Laura Vernon Foley the youngest daughter of Henry Foley, B.A. Univ. Coll., Oxford (2). Her sister Florence Maud Foley was married to Randolph Mainwaring’s brother Karl Heinrich Augustus Mainwaring. Edith Mainwaring died on 23 April 1887 at San Remo, Italy. (3)
He died in 1902 aged 63 years (4)
(1) Births Sep 1839 Mainwaring Randolph Newcastle under Lyme vol.17 page 99
(2) MAINWARING - FOLEY -August 15 at Mitcham, Surrey, by -- Randolph Mainwaring, to Edith L.V. Foley, daughter of the late Henry Foley, of Ersham House, Canterbury, and Westow Manor House, Hunts.
(3) Mainwaring - On the 23rd inst., at San Remo, Edith Laura Vernon, wife of Randolph Mainwaring, Esq., and daughter of the late Henry Foley, Esq., of Ersham House, Canterbury. The Morning Post (London, England), Wednesday, April 27, 1887; pg. ; Issue 35835.
(4) Deaths Dec 1902 Mainwaring Randolph aged 63 Edmonton vol. 3a page 213News has been received in town to-day from England of the death of Mr. Randolph Mainwaring, a well-known resident of Christchurch some years ago. The late Mr. Mainwaring filled a high position in the Canterbury Education Department before the abolition of the provinces. After that event he was well known in Canterbury as a journalist, writer, and artist. When Mr. Mainwaring left the colony to reside in England in the later eighties, he left behind a large circle of friends, who will be very sorry to hear of his death — which was not altogether unexpected, as Mr. Mainwaring was for some years an invalid. He was a brother of Mr. Eugene Mainwaring, of the Railway Land Office. Evening Post, Volume LXV, Issue 34, 10 February 1903, Page 6