In the Nancy Mitford novels there is a character called the Bolter. She is the narrator’s mother who lives in Kenya and parks her daughter on an unmarried aunt. She is always falling for unsuitable men, white hunters and people called Juan. The real-life Bolter was Lady Idina Sackville, and Frances Osborne is her great-granddaughter. Frances Osborne first learned of the Bolter when, at the age of thirteen, she read a newspaper article about her. The story of this infamous woman had been airbrushed from the family history, and the quest to retrieve the Bolter became a lifelong obsession.

In Kenya’s Happy Valley, Idina was queen. In the 1920s and 1930s she was the leader of the clique of glamorous aristocratic émigrés whose main occupation was sleeping with one another. At house parties, the Bolter wore nothing at all underneath her Kenyan tribal robes, and presided over a game