Thomas Cass was born in Yorkshire in 1817 and educated at Christ's Hospital where he was in the Royal Mathematical Foundation for four years. He then went to sea and served in the East India trade. After three years he gave this up and studied architecture and surveying, and on qualifying was employed as an assistant in the Tithe Commission Office, Somerset House. The newly founded colony of New Zealand attracted him and he obtained the post of assistant surveyor with the New Zealand Company. The Prince Rupert, in which he left England, was wrecked at the Cape of Good Hope, and with it went most of his belongings. He continued his voyage in the Antilla, reaching Auckland in December 1841. He was employed in laying out part of the city of Auckland, at the Bay of Islands, and to the northward where he surveyed the town of Kororareka and prospected road lines to Hokianga and Whangaroa. He then surveyed the north shore of Auckland and after that was again at the Bay of Islands until late in 1844 when the New Zealand Company discharged him owing to the reduction of the survey department. It was then that his service at sea stood him in good stead. He became second, later chief, mate of the Government brig Victoria and was present at the destruction of Kororareka in 1845, and at the operations against Te Rauparaha in Cook Strait in 1846. Other adventures included the transport in custody from Otago to Wellington of Langlands and Davis, two of Canterbury's first bushrangers who had robbed the Greenwoods at Purau in 1845.
In 1847 Cass returned to England to press his claim for compensation for the loss of his position as surveyor. The formation of the Canterbury Association led, in July 1848, to the dispatch of an advance party under Captain Joseph Thomas, with Cass and Torlesse as assistant surveyors, to select a site for the proposed Church of England settlement. They sailed in the Bernicia, reached Wellington in November, hired a cutter, the Fly, and with William Fox, the New Zealand Company's agent, and five survey, hands proceeded to Port Cooper, landing at Purau on 15 December. Cass began by making the first detailed survey of Lyttelton Harbour, previously roughly charted by M. Fournier of the French corvette Heroine. When the site for the Canterbury settlement had been decided, he made the first trigonometrical survey of the Christchurch district preparatory to the laying off of the town itself. He next surveyed the Lincoln and Ellesmere districts. In January 1851, on Captain Thomas's precipitate departure, he became Chief Surveyor in Canterbury, a position which he held until March 1867 when he retired on account of his health – he suffered from chronic asthma. He played a prominent part in the life of the young community. In 1853 with Sewell and the Rev. R. B. Paul, he fixed the site of Christ's College. He was one of the members of the first Provincial Council of 1857. He was in the Executive Council under Moorhouse and again under Bealey. For 10 years he was a member of the Canterbury Waste Lands Board, and served on various commissions connected with the development of communications in the province.
In 1867 he revisited England and succeeded Crosbie Ward as immigration agent for Canterbury. While he was there, Samuel Butler painted a portrait of him which is now in the Canterbury museum. Cass returned to Christchurch in 1868. He was a member of the Church of England and served as churchwarden at St. Michael's. He married the widow of David Theodore Williams in 1856. They had no family and after his wife's death in 1885, he lived very quietly with his stepson, C. Hood-Williams, until his death in Christchurch on 17 April 1895.
Cass filled the post of Chief Surveyor with distinction, and brought to the deliberations of the various bodies of which he was a member a profound knowledge of the province. He was a delightful character, known affectionately to all as Tommy, and noted for his benevolence. His name is perpetuated in a township, a river, a bay, and a Banks Peninsula peak.
by Peter Bromley Maling, G.M., M.SC.(N.Z.), M.B., B.S. (LOND.), M.R.C.S., L.R.C.P., Medical Practitioner and Author, Christchurch.
- The Torlesse Papers (ed.) Maling, P. B. (1958)