Huth is the daughter of the actor Harold Huth. She left school at age 16 in order to paint and to study art in both France and Italy. At 18 she travelled, mostly alone, across the United States before returning to England to work on a variety of newspapers and magazines. She married the journalist and travel writer Quentin Crewe in the 1960s and with him had a daughter, Candida. She presented programmes on the BBC, including How It Is and Why and Man Alive.
She is now most recognised as a successful writer. She has written three collections of short stories and eleven novels, including Land Girls, which was made into the 1998 feature film The Land Girls starring Rachel Weisz and Anna Friel. She also writes plays for radio, television and stage, and is a well-known freelance journalist, critic and broadcaster. Her play The Understanding ran at the Strand Theatre in 1982 and starred Ralph Richardson and Joan Greenwood.
She has been married to a don, James Howard-Johnston, since 1978. They live in Oxfordshire and have one daughter, Eugenie.