She was named after her mother's great-grandmother Marcia Vavasour and educated at the Convent of the Sacred Heart, Woldingham, Surrey.
In 1975, her father became Duke of Norfolk, due to the death of a second cousin whose children were all daughters, and she became Lady Marcia.
[1] She was a sister-in-law of Sir David Frost, his widow being her elder sister, Lady Carina Fitzalan-Howard.
Other television roles included appearances in Upstairs, Downstairs, Shelley, Nancy Astor, The Professionals, Brush Strokes, Goldeneye: The Secret Life of Ian Fleming, Spymaker: The Secret Life of Ian Fleming, Murder Most Horrid, Midsomer Murders, Under the Hammer and Poirot: Evil Under the Sun.
Films include Being Julia with Annette Bening, Importance of Being Earnest and An Ideal Husband with Rupert Everett.