Louisa was a great-niece of the 6th Duke of Devonshire and the sister of Spencer Cavendish, the future 8th Duke. At age 19 she was in charge of the housekeeping at all of the many Devonshire homes and acted as the unmarried Duke's chatelaine at Devonshire House in London.

In the story... Louisa's father, the future 7th Duke, has been a widower for 14 years and has no inclination to remarry. The Devonshire dukedom has been without a duchess for 43 years and looks as if it will be without one for the whole of the 6th and 7th Dukes' tenures. Louisa is aware of Spencer's fancy for Diana and befriends her, desirous of the dukedom once again having a duchess.

Louisa's father, who lives at Holker Hall in Lancashire, falls ill with typhoid in December 1854. She leaves London to care for him at home. Diana replaces Louisa as chatelaine at Devonshire House, partly through Spencer's influence.