Stephen Frears Director Meryl Streep Florence Foster Jenkins Actor Hugh Grant St. Clair Bayfield Actor Simon Helberg Cosme McMoon Actor Rebecca Ferguson Kathleen Actor Nina Arianda Agnes Stark Actor David Haig Carlo Edwards Actor John Kavanagh Arturo Toscanini Actor Christian McKay Earl Wilson Actor John Sessions Doctor Actor Mark Arnold Cole Porter Actor Neve Gachev Friend of Florence Actor Josh O'Connor Donaghy Actor Elliot Levey Edgar Booth Cunningham Jr Actor David Menkin Carlton Smith Actor Paola Dionisotti Baroness Le Feyre Actor Nat Luurtsema Tallulah Bankhead Actor Sid Phoenix Corporal Jones Actor Nicholas Martin Screenwriter Michael Kuhn Producer Tracey Seaward Producer Cameron McCracken Executive Producer Christine Langan Executive Producer Malcolm Ritchie Executive Producer Danny Cohen Cinematographer Valerio Bonelli Film Editing Alexandre Desplat Original Music Alan MacDonald Production Design Patrick Rolfe Supervising Art Direction Caroline Smith Set Decoration Consolata Boyle Costume Design Leo Davis Casting Lissy Holm Casting Kathleen Chopin Casting