In Mexico on 20 August 1966, Lerew married Josephine Henriette Oude Reimerink, a Dutch national he had met three years earlier. He was promoted ICAO's Chief of Flight Branch in April 1969, in which capacity he served until retiring from the organisation in 1972. In retirement, Lerew and his wife restored houses and travelled extensively. Their expeditions resulted in two narrow escapes, in December 1974 when they tired of the oppressively humid weather in Darwin and left just before Cyclone Tracy struck on Christmas Day, and in February 1976 when they decided to camp well away from Lake Atitlan, Guatemala, which was devastated soon after by an earthquake that left over 22,000 people dead. The couple eventually settled in Vancouver, where John Lerew died of cancer on 24 February 1996, aged eighty-three. He was survived by Josephine and the children of his first marriage.