In the parallel universe, Leslie Howard is still alive and still acting in 1971 as World War II never occurred. In reality, Howard was killed when his plane was shot down by a flight of eight Luftwaffe Ju-88C "Zerstorers" or heavy fighters over the Bay of Biscay on June 1, 1943.
In the parallel universe, John F. Kennedy likewise served as the U.S. President but he was never assassinated. In 1971, he was elected Secretary General of the League of Nations.
In the parallel universe, neither World War II nor the Vietnam War ever happened.
In the parallel universe, heart transplantation is unknown to medical science in 1971. In reality, Dr. Christiaan Barnard performed the first heart transplant on Louis Washkansky on December 3, 1967.
The two universes diverged in 1938.