Janovický was born in Plzeň as Bohuš František Šimsa. Growing up under the German occupation, he studied piano from an early age and later composition with Josef Bartovský (1884-1964). In 1949 he was unsuccessful in applying to study at the Academy of Performing Arts in Prague (HAMU) for political reasons. (The Czech coup of February 1948 had resulted in Communist Party control over the Czech Government). So in October of that year he left with his future wife Sylva Maiwaldová for Germany, arriving a year later in England.