Jean Elizabeth Muir, FCSD was an English fashion designer. Jean Muir was born in London, the daughter of Cyril Muir, a draper's floor superintendent, and his wife, Phyllis Coy. Her father was an Aberdonian, and Muir would attribute her creative pragmatism and self-discipline to this Scottish ancestry. Her parents separated while she was still a child, and she and her brother Christopher were brought up in Bedford by their mother.
She was educated at the Bedford Girls' Modern School in Bedford. While she was academically unimpressive, she showed a precocious talent for needlework, claiming to have been able to knit, embroider, and sew by the age of six.
At the age of seventeen, she left school and went to work at an electoral registration office at Bedford Town Hall. She then moved to London, where she worked briefly in a solicitor's office before taking a stockroom job at Liberty & Co in 1950. She worked her way upwards to selling over the counter, and then despite her lack of formal art college training, was given the opportunity to sketch in Liberty's ready to wear department. This would serve as her apprenticeship, and led to her gaining a job as designer for Jaeger in 1956. While there, she helped develop the Young Jaeger fashion label.