One of the six lively Mitford girls, daughters of Lord Redesdale, whose early lives were chronicled in Jessica Mitford's book Hons and Rebels. Two (Jessica and Nancy) became famous socialists, two (Diana and Unity) became famous fascists, and Debo married a duke.

Born in 1917, Jessica was always known as Decca, but she kept the name Jessica on her books. The other best known of hers was The American Way of Death, a condemnation of the funeral trade.

She and her first husband Esmond Romilly were both socialists from an early age, and she already knew his writings on the fight against fascism before meeting him. They ran off to Spain together to help the Loyalists in the Spanish Civil War. Lord Redesdale persuaded the government to send a destroyer to rescue her, but she declined, and made the rift with most of her family irreparable.

They went to the United States, living poorly, and had a daughter Constancia. Romilly, a nephew of Winston Churchill, joined the Canadian Air Force and flew missions against Germany, but was lost over the North Sea. Decca asked Churchill to confirm his death.

She got a job at the Office of Price Administration (OPA), where she became close friends with Bob Treuhaft, a lawyer who worked on civil rights cases. They were married in 1943 after moving to California, and then joined the Communist Party. Both were subpoenaed before the House Un-American Activities Committee in 1953, but refused to cooperate. They left the party in 1958.

In 1955 they visited her homeland England then went to his, Hungary. They were by now prominent campaigners, working against exploitation and racism. In 1961 Decca found herself trapped along with Martin Luther King in a Baptist church while a racist mob rioted outside.

But amid this she wrote her renowned (auto)biography Hons and Rebels, published in 1960. A "Hon" (an "Hon"?) was an "honourable", the courtesy title given to the girls as daughters of a lord. This was later adapted for TV.

Bob Treuhaft did a lot of work with trade unions, especially longshoremen, and was appalled at how much of their hard-earned money they could spend on a funeral. This spurred Decca into her other great book, published in 1963, a sweeping condemnation of undertakers and the industry.

Other books by Jessica Mitford include Kind and Usual Punishment on the prison system, a study of the 19th-century heroine Grace Darling, and A Fine Old Conflict. In their house Maya Angelou first began writing I Know Why the Caged Bird Sings.

Decca died in August 1996. Her last request was that SCI, the large funeral organisation she had so often battled, should pay for her funeral, because of all the publicity she had given them. The cremation container cost the grand total of $15.45. Her husband Bob has just (11th November 2001) died, at the age of 89.

Joanne Rowling named her daughter Jessica after her.