Jean Marsh, the acclaimed actor and writer renowned for co-creating and starring in the influential 1970s ITV drama “Upstairs, Downstairs,” has passed away at the age of 90 due to complications from dementia at her home in London. The series, set in an aristocratic house during Edwardian London, poignantly examined themes of class and social change and garnered numerous awards. Michael Lindsay-Hogg, a close friend of Marsh, confirmed her death, marking the loss of a significant figure in television history.