Hunter was born at Hoveton, Norfolk and went to school across the River Bure in Wroxham. He left school at 14 and worked on his father's farm near Norwich. He enjoyed dinghy sailing on the Norfolk Broads, wrote natural history notes for the local newspaper, and wrote poetry, some of which was published while he was in the Royal Air Force during the Second World War.
In the year of that first publication he married Adelaide Cooper, with whom he had one daughter. After the war he managed the antiquarian books department of Charles Cubitt in Norwich. Four years later, in 1950, he established his own bookshop on Maddermarket in the city.
From 1955 until 1998 he published a Gently detective novel nearly every year. He retired to Brundall in Norfolk where he continued his interests in local history, natural history, and sailing.
In 2007 the BBC broadcast an adaptation of 'Gently Go Man' under the title George Gently. Two more stories, 'The Burning Man' (adapted from the book 'Gently Where the Roads Go') and 'Bomber's Moon', were broadcast by the BBC in July 2008. The role of George Gently is played by Martin Shaw. A second series was broadcast in 2009.