He had Alzheimer's disease, said his wife, Zena Sheardown.
In the events that became known as the "Canadian Caper," Sheardown was serving officially as the top immigration official at the embassy in Tehran. Recounting the 1979 ordeal, historian Robert Wright wrote that the portly, ruddy-faced Sheardown "exuded the sort of quiet but unyielding resolve that made him a natural leader in a crisis."
The strife began when an Iranian mob seized the U.S. Embassy on Nov. 4, 1979, and took 52 Americans hostage in retaliation for Western support for the recently deposed shah. As was retold in the Ben Affleck film "Argo" (2012), six Americans managed to evade the hostage takers.
Sheardown became a vital -- but necessarily discreet -- point of contact for the desperate Americans seeking sanctuary. When the mission proved successful, he was often overshadowed in the public imagination by more prominent government officials.
He figured in a 1981 Canadian television film, "Escape from Iran," and later in books as a loyal and daring supporting player. More noticeably featured were Canadian officials including Prime Minister Joseph Clark, Foreign Minister Flora MacDonald and Ken Taylor, the gregarious ambassador to Iran lauded by Time magazine as the rescue plot's "mastermind and instant hero."
Most recently, Victor Garber portrayed Taylor in "Argo." Sheardown was not a character in the film.
But as Kathleen Stafford, one of the American "house guests," recalled in an interview Tuesday, Sheardown was "a lifesaver" at a time when she and her colleagues feared for their safety.
In the days after the U.S. Embassy takeover, the six fugitive Americans assumed that the turmoil would subside quickly. They hid in the homes of their abducted colleagues and spent brief periods in other embassies, but tensions continued to build in the city and their security became ever more precarious.
Robert Anders, another of the American diplomats seeking haven, knew Sheardown and called him to request official protection.
"Why didn't you call sooner?" Sheardown replied.
Five of the six Americans arranged passage to the Sheardown residence in the suburbs north of Tehran and arrived on Nov. 10. Sheardown, who had helped obtain permission from Ottawa, phoned Taylor to say that the "house guests" had arrived. They were soon followed by the sixth American, Henry Lee Schatz, who had been hiding at the Swedish Embassy.
The Taylors took Stafford and her husband, Joseph. The other four - Anders, Schatz and Mark and Cora Lijek - remained with the Sheardowns.
"We were under surveillance," Sheardown once told an interviewer. "We had tanks at one end of the street and a fellow that walked up and down. They were always suspicious."
During the two months they quartered the Americans, the Sheardowns took creative precautions to avoid tipping off the authorities. To feed the extra mouths - especially at Thanksgiving and Christmas - they bought groceries at different stores to disguise the amount of food consumed at the home.
Sheardown took garbage with him on the route to work, to camouflage the amount of refuse they were generating. The CIA arranged preparations for the Americans' departure, which became urgent as the Iranians erected roadblocks around the city and rumors of the house guests spread among Western media.
On Jan. 28, 1980, the six Americans were spirited out of the country with fake Canadian passports and disguised as members of a Hollywood film crew. Schatz once told The Washington Post that his suitcase had been stuffed with strategic items, including a T-shirt advertising the Canadian beer Molson Ale.
Soon afterward, the Sheardowns also left the country. The remaining American captives from the embassy were held in Iranian custody for almost another year - until Jan. 21, 1981, after Ronald Reagan's inauguration as president.
John Vernon Sheardown was born in Sandwich, now part of Windsor, Ontario, on Oct. 11, 1924. At 18, he joined the Canadian air force and served in Europe during World War II. He once broke both legs after jumping from a plane at low altitude on a training mission over England.
After the war, Sheardown spent several years in the Canadian army before joining the immigration service in the early 1960s and later the foreign service. He retired by the early 1990s.
His first marriage, to Kathleen Benson, ended in divorce. In 1975, he married Zena Khan. Besides his wife, of Ottawa, survivors include two sons from his first marriage, Robin Sheardown and John Sheardown Jr.; two sisters; and six grandchildren. A daughter from his first marriage, Jackie Hunter, died in 2007.
In the aftermath of the Iranian crisis, Taylor and Sheardown received the Order of Canada, one of their country's highest civilian honors. Sheardown waged a public and ultimately successful campaign to recognize his wife with the same award. Patricia Taylor, the ambassador's wife, also received the prize.
"The men went to the office every day," Sheardown told The New York Times in 1981. "The wives had a 24-hour responsibility. What we did was a normal extension of our functions. What they did was extraordinary."
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