Born in Wellington on 8 July 1866, Byron Paul Brown was the seventh of fourteen children of Jane Winton and her husband, Arthur Brown, a carpenter who later became a cabinet-maker and shipwright. He attended Mount Cook Boys' School, but his parents could not afford to let him take up a scholarship to Wellington College. Nevertheless, Byron continued to educate himself throughout his life, mainly by reading and reciting the works of Shakespeare and Dickens. He later claimed that he had been brought up on 'the porridge pot and the Bible'.
As a young man Brown spent several years in Australia working as a drover and bushwhacker. Returning to New Zealand in the early 1890s with 150 sovereigns in his pocket, he moved to Ōtaki and opened the Ōtaki General Provider Store in the township's Main Street. He soon established branches in the neighbouring villages of Manakau, Ōhau and Waikanae, and also acted as an auctioneer and commission agent. On 4 February 1895, in Ōtaki, Brown married Susannah Bright, daughter of a local entrepreneur and landowner. They were to have a daughter and a son.
Byron Brown, who had become one of New Zealand's youngest justices of the peace in 1896, began to take an increasingly active part in local affairs. He became a director, and later chairman, of the Ōtaki–Manakau Co-operative Dairy Company, unsuccessfully contested the Ōtaki parliamentary seat as an independent in 1905, 1908 and 1911, and was chairman of the Ōtaki Town Board from 1918 to 1920. In the latter role he is said to have temporarily refinanced the board, using the name of another person, when town moneys dried up.
About 1919 Brown organised the completion of Tasman Road from the township to Ōtaki Beach. This provided access to several hundred acres of Māori land which he had bought and was offering for sale and settlement. As a further encouragement to buyers, he built the Kiosk guest-house and cabins, with accommodation for 90 holiday-makers. It later became the Capitol guest-house, and in 1989 a restaurant named in Brown's honour was opened.
Brown was a member and patron of a number of Ōtaki sporting groups, including the surf life-saving, swimming, golf and tennis clubs, and he donated several trophies. A gifted elocutionist, he gave regular public readings from Dickens and Shakespeare, organised summer speaking competitions for children, and was president and judge for the Wellington Competitions Society. As 'Uncle Sandy', from 1931 he hosted a popular weekly children's programme on 2ZW, Wellington's first commercial radio station.
Byron Brown's greatest contribution to the community of Ōtaki was his gifting of large areas of land to various causes. In the 1930s he donated some 70 acres to establish the Raukawa (later Ōtaki) Children's Health Camp. He also gave land for the Feltham Children's Rest Home, tennis courts, several churches and a motor camp. In 1933 he presented a house and section in the centre of Ōtaki township to the borough council for a library; he opened it in 1936, donating a bust of Dickens.
With an environmental foresight unusual for his time Brown purchased a 33-yard-wide strip along the Ōtaki Beach foreshore for development as a marine parade. He dreamed that Ōtaki would become a centre of tourism, aviation and film-making. In 1921 Brown had helped to establish the Ōtaki Moving Picture Company (also known as Māoriland Films), a short-lived venture that produced three films. One, Historic Ōtaki, includes scenes of Brown's Kiosk and of him performing a haka.
Over the last 27 years of his life Byron Brown divided his time between homes in Wellington and Ōtaki Beach. He died in Wellington on 21 August 1947, survived by his children. He was buried beside his wife, Susie (who had died in 1925), in the cemetery of Rangiatea Church, Ōtaki.