On leaving the RA, she worked with her sister Doris on murals for the Queen Mary and the Queen Elizabeth liners and produced notable portraits. She also provided illustrations for several books, including Sophy Cassmajor by Margery Sharp, published in 1934.
While volunteering as a nurse at St. Mary’s Hospital during the Second World War, Zinkeisen made pathological drawings of war injuries for the Royal College of Surgeons. She was awarded RDI in 1940. In her self-portrait of 1944 (held in the NPG), clutching a bundle of paint brushes and wearing the bracelet of the St John’s Ambulance Brigade, for which she was volunteering, her gaze leaves the viewer in no doubt as to her professional status.