Film:
* The Remains of the Day (1993) - as Miss Kenton
* The Wedding Guest (1995) - as Katherine
* The Importance of Being Earnest (2002) - as Gwendolen Fairfax
* The Lady in the Van (2015) - as Mary Shepherd
* The Guernsey Literary and Potato Peel Pie Society (2018) - as Isabel
* The Personal History of David Copperfield (2019) - as Betsey Trotwood
* The King's Speech (2010) - as Queen Mary
* The Secret Garden (1993) - as Martha Sowerby
* The House of Mirth (2000) - as Gertrude van Os
* The Importance of Being Earnest (1992) - as Gwendolen Fairfax
Television:
* House of Cards (2013-2015) - as Claire's mother, Elizabeth
* The Last Kingdom (2015-2020) - as Queen Æthelflæd
* The Mystery of Edwin Drood (1985) - as Helena Landless
* The House of Eliott (1991-1994) - as Lady Virginia Eliott
* Sense and Sensibility (1981) - as Marianne Dashwood
* The Jewel in the Crown (1984) - as Barbie Batchelor
* An Unsuitable Job for a Woman (1982) - as Jane
* The Lord Peter Wimsey Mysteries (1987) - as Bunty
* The Shadow in the North (1988) - as Margery
* The Queen's Nose (1990) - as The Queen
This is not an exhaustive list, but it gives you a good overview of some of her most notable work. She has also done extensive work in theatre, particularly in the United Kingdom.