Diana was born into the Spencer family, a family of British nobility with royal ancestry and was the fourth child and third daughter of John Spencer, Viscount Althorp, and Frances Roche. She grew up in Park House, situated on the Sandringham estate, and was educated in England and Switzerland. In 1975—after her father inherited the title of Earl Spencer—she became known as Lady Diana Spencer. She came to prominence in February 1981 when her engagement to Prince Charles was announced to the world.

Diana gave her sons wider experiences than was usual for royal children. She rarely deferred to the Prince or to the Royal Family, and was often intransigent when it came to the children. She chose their first given names, dismissed a royal family nanny and engaged one of her own choosing, selected their schools and clothing, planned their outings, and took them to school herself as often as her schedule permitted. She also organised her public duties around their timetables.

The Princess developed an intense interest in serious illnesses and health-related matters outside the purview of traditional royal involvement, including AIDS and leprosy. In recognition of her effect as a philanthropist, Stephen Lee, director of the UK Institute of Charity Fundraising Managers, said "Her overall effect on charity is probably more significant than any other person's in the 20th century."

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