Violinists Norbert Brainin , Siegmund Nissel and Peter Schidlof were forced to leave Vienna for London because of their Jewish origin after Hitler 's Anschluss of 1938 . Because of their Jewish origin , violinists Norbert Brainin , Siegmund Nissel and Peter Schidlof ( later violist ) were driven out of Vienna after Hitler 's Anschluss of 1938 .