Thomas Brydone was born on 14 April 1837 at West Linton, Peeblesshire, Scotland, the son of Thomas Brydone, a shepherd, and his wife, Margaret Stewart. When Thomas junior was young the family moved to Blair Athol and he was educated at the Perth Academy. He then worked as a land steward for the earl of Buchan and, later, the duke of Hamilton. Moving to England he worked as a travelling inspector with the West of England Land Improvement Company before being employed by Lord Falmouth at his estate in Kent. He was back in Scotland by 1861 and returned to the service of the earl of Buchan. A partnership in Young's Paraffin Oil Company in 1866–67 proved unprofitable: the venture failed when paraffin oil began to be imported from America.
On 8 March 1866 a large pastoral association, the New Zealand and Australian Land Company, was formed in Glasgow. In 1867 Brydone was appointed superintendent of its New Zealand properties, located mainly in Otago and Southland. He travelled to Dunedin via Melbourne, Australia, taking up his post in 1868. The job was formidable, for the scattered estates presented a wide variety of terrain and climate. There were also tensions and jealousies between the New Zealand agents and the parent company in Scotland. Brydone had to rely on his wide experience of land management in Scotland and England to make any progress during his first nine years in office.
In 1877 the company amalgamated with the Canterbury and Otago Association, another large and prosperous land company with essentially the same directorate, and under the control of the same general manager, James Morton of Glasgow. The new company was, like its predecessor, known as the New Zealand and Australian Land Company. Its New Zealand superintendent, William Soltau Davidson, returned to Scotland in 1878 to replace Morton as general manager, and Brydone took up his post. While the amalgamated company went through stressful times after 1877, the new organisational structure avoided unnecessary duplication and competition and enabled Brydone to work more successfully than in earlier years.
Brydone was also involved in other aspects of farming, and did much to encourage the development of agriculture and pastoralism in the South Island. He helped to establish the Otago Agricultural and Pastoral Association in 1876, and was an office bearer for much of the rest of his life. It was Brydone who suggested to Davidson that the company's huge and unprofitable estate at Edendale, Southland, could be utilised for dairying. In 1882 the company established New Zealand's first dairy factory at Edendale, and Brydone actively followed Davidson's guidelines for the development of butter and cheese manufacture. Brydone's applications of lime and other fertilisers to the sour soils of Edendale encouraged other farmers to follow his lead in transforming unproductive land into some of the best pasture in the country.
Thomas Brydone's greatest single contribution to agricultural and pastoral development in New Zealand was the part he played in setting up the frozen-meat industry. When Davidson decided to experiment with shipping frozen meat to Britain, Brydone was responsible for supervising the selection of stock, building slaughtering facilities at Totara in North Otago, and organising the overland transport of the carcasses by rail to Port Chalmers. He also supervised the loading of the cargo aboard the Dunedin in February 1882. All this was done under novel conditions which put much investment capital at risk. Brydone realised that one success would not guarantee the future of a whole industry, and that capitalising on the achievements of the first shippers of frozen meat called for resourcefulness and plain hard work. He delivered a paper to the Australasian Stock Conference in Sydney in 1892, describing the huge problems of the first 10 years of the infant trade. His optimism for the future was unshakeable.
In addition to his work for the New Zealand and Australian Land Company, Brydone found time to be a farmer, a director of the Milburn Lime and Cement Company and chairman of the Kaitangata Railway and Coal Company. He was involved in the development of the Burnside Freezing Works near Dunedin, founded by the original New Zealand Refrigerating Company.
Early in April 1904 Thomas Brydone left Dunedin for London seeking medical advice about an internal complaint. He did not long survive the voyage and died at London on 17 June 1904. There is no record of his having married.
Brydone was a significant figure in the development of New Zealand agriculture. Men such as Davidson may have originated the frozen-meat trade, but Brydone's capable management of the practical side of the business ensured its success. His contribution to the development of dairying is, if less heralded, perhaps even more noteworthy. A memorial at Totara commemorates his achievements, and a plaque at the Edendale Dairy Factory records that 'He filled every unforgiving minute with sixty seconds'.