Lavinia Jane Kelsey was born in South Hackney, London, England, on 23 February 1856, one of three children of Lavinia Owen and her husband, Thomas Kelsey, a braid manufacturer. Her mother died when she was three and her father married again, having a large second family. Lavinia attended a private boarding school in Hampstead, where she developed lifelong interests in education, art and literature.
At the age of 21 she emigrated with her brothers, Thomas and Arnold, to New Zealand, and settled in Dunedin. Lavinia, who never married, worked as a governess, and then began taking girls into her own home as pupils. About 1883 she moved to Christchurch briefly, and then returned to England to visit her father. While there she learned about kindergarten work from a sister-in-law, who had been trained by the Froebel Society. She became interested in Friedrich Froebel's ideas of appealing to children's imaginations rather than just concentrating on facts, and felt they should be applied to all levels of education. On her return to Dunedin she began doing 'something in the kindergarten way' in her own private school.
When Rutherford Waddell, the Presbyterian minister whose services Lavinia Kelsey sometimes attended, began planning an organisation to take children off the streets in the very poor area around his church, he asked her advice as well as that of Rachel Reynolds and Mark Cohen. After a public meeting in March 1889, the Dunedin Free Kindergarten Association was set up and Lavinia Kelsey was made the first honorary secretary. She knew of a woman teacher in Christchurch, W. Wienicke, who was brought to Dunedin to begin the first kindergarten in the Walker Street mission hall.
Lavinia Kelsey was closely involved with the kindergarten during its first years. As honorary secretary she wrote enthusiastic annual reports about the changes in the children who attended the kindergarten. Dullness and apathy were being replaced by vitality; 'Every sense is being called into exercise, cultivated, and refined.' Money for the kindergarten was always hard to find, and she encouraged a fund-raising scheme through the children's page of the Otago Witness, writing vivid letters describing kindergarten activities. She was influential in the provision of training, insisting that a well-trained teacher needed two years of experience working with small children before being allowed to take charge of a kindergarten. Instruction was given to trainees not only by Wienicke, but by such eminent teachers as David Renfrew White of the Dunedin Training College, and David Con Hutton of the Dunedin School of Art and Design.
After some years Lavinia Kelsey had to retire as secretary, because of the needs of her own teaching work, but she remained on the committee of the association. In 1912, as president, she was responsible for inviting representatives from kindergarten associations in other centres to a conference in Dunedin to discuss their views and methods, and to consider forming a New Zealand union; this was established the following year. The Yaralla kindergarten in North Dunedin was later renamed the Kelsey–Yaralla kindergarten in her honour.
During the early 1900s Lavinia Kelsey had a school with premises in Moray Place, separate from her home in Cargill Street. After going overseas for a 'wander' year in 1905, she went back to holding classes in literature, history and French in her home. She retired from teaching about the age of 60, although she continued to be involved in various kinds of education work. During the First World War she began a group, the Toy Makers' Society, which provided therapy for bed-ridden soldiers in Dunedin Hospital. This work spread to other wards and continued until the influenza epidemic of 1918.
Lavinia Kelsey was prominent in the movement to establish a crematorium in Dunedin and took an active interest in the affairs of the Dunedin Public Art Gallery and the Dunedin Public Library. She was particularly remembered for the classes she held for women, on art, literature, classical mythology and other subjects, pouring such passionate energy into her talks that her listeners felt it was an adventure to listen to her. She 'kept state' in her home, a small intense figure in Victorian clothes, until she was 92, dying in the public hospital after three days of illness on 16 June 1948.