James Dilworth, the son of Mary Bell and her husband, John Dilworth, a farmer, was born probably at Donaghmore, County Tyrone, Ireland, on 15 August 1815. After a sound education at the nearby Royal Dungannon School, James worked first on his father's farm and then in an Irish bank.
Probably in 1839 James emigrated to New South Wales, then in 1841 he sailed to New Zealand on the Planter. After a brief period exploring prospects at a number of settlements, this lanky young Irishman settled in Auckland as accountant to the New Zealand Banking Company in Princes Street.
Overdue bills ultimately forced the bank to wind up in 1845. This did not deter Dilworth. Equipped with capital (presumably from his family) he had already turned to land buying. Late in 1842 he had bought six acres of Parnell land on which he put a house, and in 1845 bought nearly 100 acres at Takapuna. In 1844 he had acquired more than 150 acres between Mt St John and Mt Hobson. Setting himself up as a farmer he continued to add to this estate, which became in time the most valuable of all the farms in this vicinity. He also acquired properties in the township and throughout the Auckland province. He was the astutest of land buyers.
In the 1860s Dilworth prospered. With the continued growth of Auckland's population his suburban farm, three miles from town, shot up remarkably in value. He also had two strokes of luck: the outbreak of the New Zealand wars led to valuable commissariat contracts, and the government decision to run the tracks of the trunk railway through his estate put generous compensation money into his pocket. In 1882 his properties were estimated to be worth £81,044. However, this figure does not take into account the 225,000 acres of recently bought Māori land in the upper Thames (Waihou) valley, or the Whāiti–Kuranui block, which Dilworth held in partnership with another Ulsterman, the impetuous Joseph Howard.
This speculation miscarried completely. The Whāiti–Kuranui proprietors, and a four-man syndicate which owned the adjoining Pātetere block, in 1882 jointly sold their huge landed estate (just on 600,000 acres) to a London company, the New Zealand Thames Valley Land Company. The incorporation brought no ready cash to the pockets of the indebted New Zealand speculators, however, and, because of deepening rural depression, the company failed to sell its farm allotments. Ultimately the banks foreclosed. By the end of the 1880s Dilworth alone of the seven speculators was not insolvent. Even so, it is estimated that he lost £40,000 or more because of this venture. As an investor in a number of Auckland companies, such as the Auckland Fibre Manufacturing Company, the Thames Valley and Rotorua Railway Company, and the New Zealand Frozen Meat and Storage Company, he suffered losses in other directions as well.
Little is known about Dilworth's private life. He was reserved and left few personal records. On public occasions he merged into the background Cheshire cat-like, leaving speechmaking to others. He was not fond of long explanations. For one who could be gruff and stern he could also be very kind. Loyalty he esteemed: his friends remained true for life. He favoured Irish people as friends, whether they were Catholic or Protestant.
On 12 July 1853 at Ōtāhuhu James Dilworth had married Isabella Hall of Ōtāhuhu. Originally from Ulster, Ireland, she was 24 and he 38. Their marriage was a happy one, although childless. Tradition has it that around 1880 Dilworth built his third and last house on the estate for Isabella. This homestead, although lacking the external impressiveness of most homes of the well-to-do of that era, was a fine spacious house approached through an avenue of shady trees.
Dilworth has an impressive record of public service. He was for 27 years from its opening in 1847 a trustee of the Auckland Savings Bank. As an ardent Anglican of the low church persuasion – he looked askance at 'popish surplices' and excessive ritual – he was a longstanding member of the Diocesan General Trust Board. He served on the Auckland Provincial Council for eight years. Public causes he supported included the kindergarten movement and the YMCA. Education was close to his heart, and he was a member of the Auckland University College council for the last four years of his life.
During his latter years Dilworth suffered from a neurological complaint, perhaps Parkinson's disease. A visitor to the homestead recalled that he shook with 'palsy'. He had a pony carriage made very low and his wife took him driving every day. After giving serious thought to the disposition of his wealth on his death, Dilworth made a will in which the bulk of the estate was bequeathed to the Dilworth Ulster Institute Trust. This was instructed to set up an institute (or school) which would take in and educate boys who were living in straitened circumstances.
James Dilworth died of peritonitis at Remuera on 23 December 1894. His estate was valued at £150,000. Isabella died on 27 February 1910. Dilworth's monument surely is Dilworth School. In less than a century it grew to be one of New Zealand's largest boarding schools.