Frances Roche Spencer hails from British nobility as a member of the aristocratic Fermoy family. She enters a high-profile marriage to John Spencer, Viscount Althorp, a union that later strains under societal pressure to produce a male heir for the Spencer earldom. The subsequent divorce triggers significant turmoil for Frances, leading to daughter Diana's relocation to a London boarding school. This separation forces Diana's adjustment to a new environment, impacting her storyline.

A pivotal custody battle over the children follows. Frances loses custody after her mother, Lady Fermoy, testifies against her in court. This legal defeat permanently separates Frances from Diana and Charles during their childhood. The narrative briefly notes her remarriage to Peter Shand Kydd shortly after the divorce; this development occurs off-screen and lacks prominence in depicted events.

Frances's background includes upbringing at Park House on the Sandringham estate, underscoring lifelong connections to royal circles. As Diana's mother, Frances occupies a narrative role where her choices indirectly shape Diana's early experiences, particularly the protagonist's struggles with familial instability and emotional resilience. The character's aristocratic status and adherence to social expectations of nobility provide consistent context throughout the story.