Vaughan studied classics at University College, London, married in 1966 and settled down to family life with a son and daughter, and became a teacher.
Lennon and McCartney never forgot the friend who brought them together. For a time they put Vaughan on the payroll of their Apple company, in charge of a plan that never took off to set up a school with a Sixties, hippie-style education ethos. Vaughan's wife Jan, a languages teacher, was hired to sit down with Lennon and McCartney and help with the French lyrics to the 1965 song "Michelle".
In 1977 Vaughan was diagnosed with Parkinsons disease. His book, "Ivan: Living with Parkinson’s Disease" was published in 1986 and he also featured in a documentary produced for the BBC in 1984 by Jonathan Miller about his search for a cure.
Vaughan's death touched Paul McCartney so deeply that he began to write poetry for the first time since he was a child. He wrote the poem "Ivan" about him after his death, and was published in McCartney's book, Blackbird Singing