After leaving school he joined the Ist Southland Regiment. Then, in 1943, he joined the navy and became a signalman in the Royal Navy East Indies Fleet.
He returned to New Zealand in 1945 and spent five years training at the Otago Dental School. At that time dentists used foot drills and it was tiring work.
While at university he joined a tramping club and a fencing group, and was university foil champion for three years.
He worked in Wellington for a year before moving to Whanganui and setting up a dental practice. He met and married Anne Keating, and the couple had three children - Anne-Maree, John and Celia.
His first foray into campaigning was in the 1950s, when a road was planned for one of his favourite walking places, Lake Hauroko.
"Gee, did I get angry about this road. I knew it would destroy the bush, and I realised then that man would destroy anything beautiful if they can make money out of it," he said in an interview with the Chronicle.
In Whanganui, Darrell joined the tramping club and went on many long trips. He was also a member of a ski club, drama group, fencing group, canoe club and the Returned and Services Association.
He became a board member, then the president and chairman of Whanganui Regional Museum and was one of eight who undertook a five-week expedition to the Chatham Islands to look for taiko in 1969-70.
After he left the museum board Darrell threw himself into conservation work - Forest & Bird, Native Forest Action Council, Maruia Society, Wanganui Environmental Society, Wanganui Environmental Forum, Taranaki/Whanganui Conservation Board and campaigns to save rivers and lakes from development.
One of those was a campaign against a proposal to dam the Whanganui River at Parikino; another was against native trees being felled and turned into pulp on the West Coast.
During this time he was a prolific writer of letters to the Chronicle, and in 1998 he won Forest & Bird's top annual award, the "Old Blue".
He was watching and cheering as the Department of Conservation was formed in 1987, and the Resource Management Act became law in 1991.
Never short of an opinion, he told the Chronicle in 1998 that environmentalists don't feature in honours lists because the government doesn't like them.
"Yet we're doing the Government's work for it... we're trying to save this country from falling to pieces," he said.