She began her career designing furniture in London and then worked on production drawings for the Barber Institute of Fine Arts in Birmingham.

After the end of World War II, Stjernstedt returned to England and became the first woman architect to achieve grade I status at London County Council.

It was during this time that she undertook a planning course at the Architectural Association before deciding to move to Sweden in the 1939 after visiting new housing projects on her previous holiday.

Stjernstedt returned to England after World War II and began working for the London County Council Housing Division.

She had a son, Robert (1941–2012), an ornithologist based in Africa who inherited the Stjernstedt barony on his father's death;[9][10][5] her partner in later life was Fred Parker.