Dame Jilly Cooper suffered a fatal head injury during a fall at her Gloucestershire home, an inquest was told.
The writer – known for her steamy romantic novels such as Riders, Rivals and Polo – was found by family at her home in Bisley at about 17:00 BST on 4 October.
Gloucestershire Coroners’ Court was told Dame Jilly was initially alert and taken by paramedics to Gloucestershire Royal Hospital, but her condition deteriorated.
She died in hospital, with her family present, at 08.30 BST on 5 October.
Katy Skerrett, senior coroner for Gloucestershire, reached a conclusion of accidental death and said Dame Jilly, 88, died as a result of a traumatic subdural haematoma.
Her novels often portrayed the scandals, sex lives and social circles of the wealthy horse-loving country set.
Rivals recently became a hugely successful TV series starring A-listers such as David Tennant and Danny Dyer.
When her death was announced by her children, Queen Camilla described the author as “a legend”.