Caroline Ada Insull was born in Birmingham, England, on 18 February 1874, the eldest daughter of Sarah Caroline King and her husband, Walter Horace Insull. At the time of her birth her father was described as an artist, but he was to become vicar of Roxby in Lincolnshire. Caroline, or Kitty as she was more commonly known, trained as a nurse at the General Hospital in Birmingham and was later appointed a sister at Guest Hospital, Dudley. As a young woman she was attractive, with beautiful chestnut hair, boundless energy and a sense of humour.
On 21 July 1902 she married George Edward Seville, a physician, at St Thomas's Church in Rhyl, North Wales. The couple spent their honeymoon on board the Star of Australia sailing to Fiji, where George established a medical practice. Kitty gave birth to her first child, Edward, in Suva in 1903. The Sevilles left Fiji the following year with Edward and a 10-year-old half-Fijian girl, Rosie, whose father had made her a ward of George Seville. They decided to visit Rotorua for treatment of George's rheumatism before returning to England. While in New Zealand he was invited to take up a medical practice in Morrinsville and accepted the offer.
Freed from household duties with the help of Rosie and domestic servants, Kitty Seville worked alongside her husband in his medical practice. As the sole doctor in Morrinsville, George was general practitioner for the small local European community and medical officer for the surrounding Maori settlements. Kitty soon developed a warm relationship with Maori, many of whom preferred to be treated by her, specifically asking for the 'woman doctor'.
As well as assisting her husband, Kitty Seville began an independent enterprise. In 1911, three years after the birth of a daughter, Katherine Margaret (Peggy), she opened Morrinsville's first hospital, which she named Loloma (Fijian for love). Primarily for maternity cases, the hospital also dealt with emergencies. Kitty Seville was manager, matron and midwife. At this time Bernard Freyberg (later governor general of New Zealand) came to Morrinsville to practise dentistry. He became a personal friend of the Sevilles and occasionally helped at the hospital.
The Sevilles were called on to cope with several major health emergencies. During a smallpox epidemic in 1913, hundreds of Maori were vaccinated by Kitty, George and another local doctor. While George worked in an isolation camp on the outskirts of Morrinsville, Kitty took charge of his surgery, travelling on horseback over rough tracks each day to receive instructions for her patients from her husband.
After the outbreak of the First World War Kitty Seville devoted her time to volunteer relief organisations and became a foundation and life member of the Red Cross sub-centre at Morrinsville. She sold Loloma and it continued to operate for nearly 40 years. In the 1918 influenza epidemic, an emergency hospital was established in the Morrinsville Baptist Church under Kitty's direction. At the same time she worked alongside others administering medicine, disinfecting houses and removing corpses in the surrounding district.
As George Seville became ill and increasingly dependent on alcohol, Kitty carried out much of his work. After his death in 1933 she continued her involvement in community activities. Generous and sociable, she was active in the Morrinsville Horticultural Society, boy scout and girl guide associations and the Morrinsville Women's Institute. She enjoyed sports including golf, lawn tennis and horse riding. During the Second World War she drew on her nursing experience to give lectures to Red Cross members and the regional nursing division of the St John Ambulance Brigade. She also worked with the local Lady Galway Patriotic Guild.
By the end of her long life Kitty Seville was a well-known and respected Morrinsville identity. She had readily adapted to the small country town and found many outlets for her talents there. Her health and welfare work received official recognition when she was made an MBE in 1953. The investiture took place at Waikato Hospital, Hamilton, where she spent her last two years. Kitty Seville died on 7 May 1955.