Death at Wentwater Court by Carola Dunn (1994) 216 pages
This first installment in the Daisy Dalrymple Mysteries, taking place in 1923, sets up the infrastructure of the series: Daisy, a young woman from an upper-tier British family, chooses to work for a living. Employed by a top-notch magazine, she takes photos and writes about various estates and the people who live on them. Her social status opens doors for her to be trusted by upper-echelon families, making it easier for her to learn about them and their homes.
Daisy's first assignment is at Lord Henry Wentwater's estate (she knows his daughter). Upon meeting the rest of the family, including Lord Henry's young wife, Lady Annabel, Daisy senses desperate unhappiness in the young bride, with stepchildren almost her own age who obviously resent her. To make matters more awkward, Lord Stephen Astwick, a former suitor to Lady Annabel, is staying at the estate as well, at the invitation of one of Lord Henry's sons. When Lord Stephen is found dead near a break in the ice at the pond, Daisy is present with her camera and she reluctantly takes photos of the scene, in case needed by the authorities.
Scotland Yard Chief Inspector Alec Fletcher is called to investigate, and he finds Daisy's insights (and her photographs) valuable. When Lord Stephen's death is no longer considered to be a skating accident, several in the household have reasons to be considered suspects. Through the investigation and the eventual solution to the mystery, Chief Inspector Fletcher and Daisy begin a friendship that continues through the series.