After finishing school in Switzerland Rosemary had returned to England committed to becoming a professional photographer. She claimed that her decision to be a photographer was made at the age of eight and her many childhood photos from the early 1930s bear this out. At sixteen, however, she went to Frieberg, Germany for eighteen months at her father's suggestion. There she learned to speak German under the tutelage of an eminent biologist and professor, an arrangement made by her father who had high hopes of her becoming a diplomat's wife. In Germany she had her first opportunity to be reimbursed for using her photographs in book illustrations, something that was to become a mainstay of her career for the next four decades. During this time she also pursued her love of skiing where she sometimes came across Hitler youths in ski huts. Their views would have been anathema to her. She did, however, develop a taste for gluevine (mulled wine) and perfected a recipe which many years later she often served to appreciative Canadian friends.

Back in London she gained some darkroom experience privately, experience that she was to put to good use throughout the1940s, 50s and 60s, as a free lance photographer. At nineteen or twenty, Rosemary apprenticed to a London theatre and commercial photographer. She also photographed for the Sunday Observer, Strand Magazine, Lilliput, and other publications, mainly through the Camera Press agency. Her work ranged from fashion photography to London's East End, but she also provided some illustrations for history and architecture books. She got much of her experience, including more darkroom work, contacts and leads through going on assignments with well known English photographer Bill Brandt whose work appeared in Picture Post and many other publications. He is the subject of a number of books.