The Secret Diary of Sarah Thomas brings together the personal diaries of a young woman kept between the years 1860-65. The daughter of a Baptist minister, Sarah Thomas lived in the Cotswold market town of Fairford, Gloucestershire. She was thirty-seven years old when she began keeping these diaries, unmarried and, following the death of both her parents, left in charge of the household of Milton House, along with the care of her invalid younger sister. Never intended to be read by anyone else, her diaries are highly personal, going far beyond the daily happenings of her life, and revealing her deepest and most intimate thoughts and feelings in confessional-style entries. They cover a critical period of her life, as she was faced with decisions about marriage and which of her suitors to accept.

The Secret Diary of Sarah Thomas not only reveals the private thoughts of this young woman, it also offers an insight into nineteenth-century life within this strongly independent community, with its clear social distinctions and prejudices, tucked away in a corner of the Cotswolds.