Gluck: Her Biography by Diana Souhami:
Gluck never went for long without a woman in her life and when the new one arrived she moved quickly into her orbit. Her close relationships influenced her painting far more than theories of art. While she was with Sybil Cookson, she painted Sybil’s grandfather, daughter, former lover’s daughter and the courtroom dramas about which Sybil wrote. During the years with Constance Spry, from 1932-6, she painted arrangements of cut flowers.