A math prodigy at age five, London was on the radio show Quiz Kids, and was educated at the experimental elementary school at Hunter College, New York City.
In 1948, the school was featured in Life and shows little Roy telling an arresting tale of death, transfiguration and group marriage involving Walt Disney's Mickey Mouse and Donald Duck.
To graduate at 20 from Antioch College, in Yellow Springs, Ohio, London wrote a paper that combined mathematical concepts and the precepts of theater.
In the late 1970s when London was on tour with Lynn Redgrave and performing on stage at the Huntington Hartford Theater in Los Angeles, he decided to stay in Hollywood.
As an actor, he appeared on television in programs as widely diverse as WNET's USA Writer's segment about Catcher in the Rye, (London is the only person to have professionally portrayed Holden Caulfield with J.D.
In 1992 London’s first feature film as a director, Diary of a Hitman, was released, starring Forest Whitaker, Sherilyn Fenn, Sharon Stone and Lois Chiles In the last fifteen years of his life he became a popular acting teacher in Hollywood.
It features interviews with over 50 of his students and friends, including Sharon Stone,[5][6] Sherilyn Fenn, Jeff Goldblum,[7] Patrick Swayze,[8] Patricia Arquette,[9] Hank Azaria,[10] Geena Davis,[11] Famke Janssen,[12] Garry Shandling,[13][14] Lanford Wilson, Lois Chiles, Elizabeth Berkley, Drew Carey[15] and Janel Moloney.