Charles Adnam Mountfort was born in Christchurch, New Zealand, on 9 February 1854. He was the eldest of six children of Charles Wheeler Mountfort, a farmer and civil engineer, and his wife, Mary Eliza Adnam. Charles's parents, together with his father's sister and brother, Susanna Wale Mountfort and Benjamin Woolfield Mountfort, and his wife, Emily Newman, had arrived at Lyttelton, New Zealand, on 16 December 1850 on board the first of the Canterbury Association's ships, the Charlotte Jane.
After farming for five or six years at Opawa, Charles senior and Benjamin returned to their professions. Benjamin practised architecture in Christchurch while Charles took up an appointment in 1856 as surveyor under John Turnbull Thomson, chief surveyor for Otago. Susanna Mountfort married Benjamin's business partner, Isaac Luck.
Charles senior worked in many parts of Otago and Southland on large settlement surveys of the Lindhurst and Waimumu blocks, the Southland and Otago section of the first telegraph line in New Zealand, and developments in Central Otago. He left the Otago survey department and returned to Canterbury in 1868. By this time Charles Adnam Mountfort had started training with his father. After being licensed as a surveyor, in 1874 he began work on the settlement surveys in thick bush country on the Manchester block near Feilding. He was later joined by his father and younger brother, Alfred John Mountfort, whom he trained as a surveyor. Charles Wheeler Mountfort went on to work in Wairarapa and Manawatu. He joined the Survey Department in 1878 and retired in 1883 to Napier, where he died aged 91 on 18 April 1918.
Charles Adnam Mountfort qualified as an authorised surveyor in May 1880. In the early 1880s he and his brother went to Taranaki, where they worked for the West Coast Royal Commission and the Public Works Department on location surveys for part of the Stratford–Ongarue railway. After assisting Charles with further surveys in Apiti, Alfred was engaged by the chief surveyor for Wellington, J. W. A. Marchant, to locate roads in the Pohangina district. He then joined the Survey Department and became district surveyor at Taupo and Kawhia. After returning to Canterbury he was transferred in 1917 to Mangonui, North Auckland, where he died on 17 August 1927.
Charles Adnam Mountfort joined the Survey Department in 1884. His ability was well recognised and he eventually rose to become a district surveyor. In 1888 he was a founder member of the New Zealand Institute of Surveyors. During the latter part of his career he was engaged on urban standard control surveys in Wanganui, Nelson, Napier, Feilding, Marton and Palmerston North, and on rural standard control surveys. He retired on 31 March 1923 regarded as 'a conscientious, hardworking, and efficient officer, possessed of good practical knowledge of the higher branches of geodesical survey'. His accurate work was also acknowledged. Over a 67-year period three members of one family had made a significant contribution to the survey record in New Zealand.
On 22 December 1879 at St Stephen's Church, Marton, Charles Adnam Mountfort had married Ann Barry Vaughan, a teacher who had set up a girls' school in Gisborne. They settled in Feilding and had five daughters and two sons. Ann Mountfort painted landscape scenes when accompanying her husband on his surveying trips. Because of his field work Charles was unable to take part in public life, but when at home he enjoyed entertaining. Ann Mountfort died on 21 February 1938 and Charles died at Feilding on 11 May 1941.