Marcia Williams' mother was a writer and her father was a playwright and theatre director. She spent the early part of her life in Canton, Hong Kong, Nigeria and the Middle East with her mother and diplomat stepfather. She loved books from an early age and remembers being read to almost every night; "I would often be scared, especially by fairy tales, but I never wanted the stories to end." She went to boarding school in Sussex, from where she sent weekly illustrated letters to her parents overseas.
Marcia didn't receive any formal art training. She calls herself "an obsessive illustrator. I've just always done it. I never consciously thought: that's what I want to do." She had a number of jobs, including nursery teacher, which is when she developed her taste for story-telling to young children; "I learnt what they found accessible and what they enjoyed." Giving up teaching to paint, she studied watercolour at Richmond College and held some successful local exhibitions before a friend suggested that she took her work to show Walker Books.
Marcia lives in London and has two grown-up children and three grandchildren, one extra-large dog and a cat.