Howard Florey
Alexander Fleming
Ernst Chain
Norman Heatley
Edward Mellanby
Margaret Jennings
Arthur Gardner
Ethel Florey
Charles Fletcher
Mr. Cox
Albert Alexander
Cecil Weir
The Master
Janet
Mother
Pharmaceutical Rep
Johnny Cox
Journalist 1
Journalist 2 (as Phillip Langhorn)
Radio Announcer (voice)
Charles Florey (as Harry Hosier-Beeson)
Paquita Florey (as Ambra-Lily Keegan)
Daughter
Patient