Legendary running coach Arch Jelley, who guided John Walker to Olympic gold in Canada, has died at the age of 104.

Athletics New Zealand says Jelley's coaching career spanned more than five decades and shaped generations of New Zealand middle-distance running.

His coach-athlete partnership with Sir John Walker saw Walker crack the world mile record, running it in 3 minutes 49.4 seconds in 1975, the first sub 3:50 mile in history.

Walker also won the gold medal in the 1500 metres at the 1976 Summer Olympics in Montreal under the guidance of Jelley.

Their relationship continued until Walker retired from competitive running in 1992.

Jelley was born in Dunedin on 13 August 1922 and joined the Mornington Harrier Club at 18 years old.

Athletics New Zealand says his running was put on hold by the Second World War, when he served in the navy, including Russian Convoy duty aboard HMS Bermuda. He went on to a long career in education, spending more than 20 years as principal of Sunnybrae Normal School on Auckland's North Shore.

Jelley began coaching in 1960 at Owairaka Harriers, which was the home to runner and athletics coach Arthur Lydiard. Athletics NZ says he admired and adapted some of Lydiard's methods.

Athletics NZ says Jelley coached dozens of other leading athletes, among them Olympians Christine Pfitzinger and Robbie Johnston; 1990 Commonwealth Games 10,000m bronze medallist Barbara Moore; and American miler Steve Scott, whom he guided to fifth in the 1988 Olympic 1500m final.

After stepping away from coaching in 2000, he returned at the age of 93, to guide Hamish Carson to the 2016 Olympic Games in Rio.

Jelley was awarded an OBE for services to sport and made a Life Member of Athletics New Zealand in 2024.

He once said he held the firm belief that a bad race was never the athlete's fault.

Details of Jelley's memorial service are yet to be confirmed.