She has starred in numerous British television series, including Connie (1985), The Darling Buds of May (1991–1993), Where the Heart Is (1997–2000), Rosemary & Thyme (2003–2006), and Call the Midwife (2012–2016).

Ferris also portrayed Marge Dursley in Harry Potter and the Prisoner of Azkaban (2004), Miriam in Children of Men (2006), Mrs. Bevan in Nativity!

Ferris was born on 11 May 1948 in Hanover, Lower Saxony, Germany,[1] to a Welsh mother and an English father who was serving in the Royal Air Force.

[4] She has also acted in a succession of television dramas, including Meantime, in which she played the Cockney mother of Phil Daniels and Tim Roth, Connie, Hardwicke House, Oranges Are Not the Only Fruit, Where the Heart Is, and Paradise Heights.

[5] Her roles in costume dramas include parts in television adaptations of Middlemarch, The Tenant of Wildfell Hall, Our Mutual Friend, The Turn of the Screw, Pollyanna, and Jane Eyre.

In 1996, Ferris portrayed the brutish, authoritarian school headmistress Miss Agatha Trunchbull in Matilda (a role played by male actors in the stage musical version).

She voiced Mrs. Bennett/Aunty Betty in the animated biographical film Ethel & Ernest, which was broadcast on BBC One on 26 December 2016, and played Mrs. Faulkner in Tolkien (2019).