The tag, 'Czar of Twickenham', was coined by the celebrated British film director, Michael Powell, during an interview he had with Ian Christie, as recorded in Christie's book, Powell, Pressburger and Others, London, 1978 (page 18). Michael Powell was describing to that author how he was able to film the comedy Lazybones (1935) at night, for Julius Hagen at Twickenham Studios. Given what we will discover and grow to appreciate about Julius Hagen as we journey through, and learn about, his extraordinary career in the British film industry, to hail him 'The Czar of Twickenham' is certainly more than just appropriate. As we shall see, he was in charge of every aspect of his growing film empire. Hence the excellent reason to use Powell's soubriquet as the title of this study about Julius Hagen and his contribution to the British film industry of the 1930s. Therefore, the essence of this set of two books is to provide a complete and extensive record of the films Julius Hagen produced.