David John (known as Davey) Gunn was born on 18 September 1887 at Station Peak, Waimate, the fourth of five children of Scottish parents Isabella Grierson Robertson and her husband, Alexander Gunn, a shepherd. He attended primary school at Hakataramea and at Hook, and Waimate District High School. After working for Dalgety and Company's stock and station agency he went farming on his own account at Sutton. On 10 July 1919 at Morven he married Ethel May Willetts, a confectioner. They were to have two daughters and a son.
In 1926 Davey Gunn and Patrick Fraser, an engineer from Outram, purchased the property of Hugh and Malcolm McKenzie at Martins Bay, south Westland. Fraser transferred his interest to Gunn the following year, but, undeterred, Gunn increased his landholding in 1929 by acquiring four leases totalling more than 25,000 acres in the Hollyford Valley. He then moved to the valley, establishing his base at Deadman's Hut on the banks of the Hollyford River; his wife took the children to Oamaru to be educated. His clothes reeking of smoke from Deadman's Hut, he returned to his family for brief visits only twice a year, extolling the beauties of the Hollyford, which was now consuming his whole life.
His Hollyford run was mainly heavy bush country, and initially his sole income came from the annual sale of cattle at Invercargill. This entailed a cattle drive of 175 miles and took four months. The holding never became a paying proposition, however; deer infestation ruined the cattle business, and the runs were held on a year-to-year lease. Stubborn and difficult to work with, Davey Gunn was not by nature a businessman, and the acquisition of money meant little to him.
He became a superb bushman, however, cutting tracks to give access to river flats, and building a chain of huts. He lived frugally, calling the Hollyford 'The Land of Doing Without', and had little time for 'modern inconveniences'. On 30 December 1936 a Fox Moth cabin plane crashed into the sea at Big Bay, injuring the pilot and five passengers, one of whom died soon afterwards. Gunn was present at the time and made a remarkable journey for help. He travelled from Martins Bay to Marian Corner in 21 hours – a journey that normally took four days. A plaque at Marian Corner commemorates the event, for which Gunn was awarded King George VI's Coronation Medal in 1937.
In 1936 he began guiding parties through the Hollyford, and continued doing so for nearly 20 years, later employing guides to assist him. Friendly and hospitable by nature, and possessing considerable personal charm, Gunn became a well-known and popular figure. He was respected for his bushcraft, his energy, and his knowledge of the area.
In 1950 Gunn was badly injured when he slipped over a bluff, and from that time he began to age noticeably. On Christmas Day 1955 he nudged his horse into the Hollyford River near Hidden Falls with a 12-year-old boy mounted behind him. The horse stumbled and fell, and both riders were swept away and drowned. Gunn's body was never found. He was survived by his wife, Ethel, and the children.
During his 25-year tenure of the Hollyford and Lake McKerrow district Davey Gunn opened up the area with tracks and accommodation huts, and established a reputation for complete self-reliance in extremely rugged country. He also communicated his own enthusiasm to a generation of trampers. A memorial cairn near the junction of the Pyke and Hollyford rivers bears an inscription which concludes 'all who passed this way knew him as "Davey, the Tramper's Friend".'