The demonstration goes wrong and Colin (with his same memories) finds himself in a parallel universe with significant differences from our own: John F. Kennedy is Secretary General of a still-existent League of Nations, Leslie Howard did not die in the Second World War because it never happened, and no one ever succeeded in climbing to the peak of Mount Everest.
The demonstration fails, resulting in Colin finding himself in a parallel universe with significant differences from our own: John F. Kennedy is Secretary General of an existing League of Nations, Leslie Howard did not die in World War II because it never happened, and no one has ever climbed to the peak of Mount Everest.