William Edgar Hazlett was a dominant figure in farming, thoroughbred breeding and racing in Southland for more than 30 years. His father, William Thomas Hazlett, a merchant with extensive land holdings, had married Kate Stephenson, a daughter of one of the founders of the stock and station agency Wright Stephenson and Company. William was born in Invercargill on 8 November 1905, the second son in a family of three sons and two daughters. He was educated at Waihopai School and Waitaki Boys' High School.
Hazlett's robust physique and determination brought him early prominence in rugby. When only 19 he represented Southland and in 1926 he was included in the All Black team that toured Australia. He was a loose forward, big and fast, six feet tall and weighing 15 stone. He was described as the outstanding forward of the tough South African tour of 1928, and played against the British touring team in 1930.
In 1929 William Hazlett senior took the lease of Burwood and Mavora stations in northern Southland; he already leased the adjacent Centre Hill station. William junior and his brother Jack managed the stations. On 4 November 1931, at Ashburton, he married Joan Marion Nicoll; they had two daughters and one son.
Following the deaths of his brother in 1944 and father in 1947, Hazlett became the owner of Burwood, Mavora and Centre Hill (totalling 134,133 acres). He also acquired the Chelandry thoroughbred stud at Taramoa, near Invercargill, which his father had established in 1918. Hazlett applied his formidable energies to the development of his high country properties. He ran Hereford cattle and Romney sheep, which were noted for their quality. Starting with 10,000 ewes he built his flock up to 25,000. In 1965 the government resumed the leases of the three stations for subdivision into small farms. Left with the Burwood homestead block of 1,235 acres, Hazlett purchased the adjoining Gorge station of 6,000 acres. Intensive development followed, and four years later he was running 10,000 ewes and 1,000 Hereford cattle.
Hazlett continued his father's interest in breeding and racing thoroughbred horses, working initially in partnership with his brother Jack. He was runner-up in the New Zealand trainers' championship in 1946–47 and 1948–49, and was the most successful owner in the 1941–42 season. In 1959 W. J. Hillis, who had been with the stable since 1945, was appointed trainer. Another period of remarkable success followed. For five seasons from 1964–65 Hazlett was New Zealand's leading owner.
Hazlett bred and trained his horses to be tough and versatile, capable of winning at any distance. Never afraid of adopting an innovative practice, Hazlett trained his horses to jump at an early age; they were entered in hurdle and steeplechase races when in their prime for flat racing. An outstanding product of this regime was Eiffel Tower, winner of the 1965 Wellington Cup and the 1967 Great Northern Steeplechase. The Hazlett stable, often with Hillis riding, won all the major races on the New Zealand jumping calendar as well as many important flat races.
Most of Hazlett's racehorses were bred at the Chelandry stud, where Kurdistan sired a Melbourne Cup winner, Baghdad Note, as well as such famous horses as Kumai, Koral and Eiffel Tower. Kurdistan's fillies were sought-after as brood mares. In 1966 Hazlett paid a New Zealand record price for the English galloper Lomond; the horse sired a string of winners, including Loch Linnhe, winner of the Australian Grand National Steeplechase. Hazlett did not seek public office. He was, though, a foundation member and president of the Southland Racing Owners' and Trainers' Association and the first president of the Southland branch of the New Zealand Thoroughbred Breeders' Association and a national councillor.
Dog trials were another of Hazlett's interests. He competed for many years with considerable success, and as he grew older these often took precedence over his racing activities. He was competing in a trial near Gore when he collapsed and died on 13 April 1978. Strong-willed and shrewd, he had been a successful and innovative high country farmer and had made a rich contribution to the history of the thoroughbred in New Zealand. The Chelandry stud was taken over by his eldest daughter, Mary Dalley, who moved it to Prebbleton, Christchurch. Joan Hazlett died at Invercargill on 13 October 1985.