Penelope Farmer arranged many incidents in "Charlotte Sometimes" ahead of time, based on family experiences. She later wrote that Charlotte and Emma were originally based on her mother and her mother's sister as children, having no parents and "having to be everything to each other", one being the responsible one, the other being rather difficult. She wrote, "Emma and Charlotte have grown in their own ways and aren't exactly based on my mother and her sister now, but this is where it started." Penelope Farmer's mother, Penelope Boothby, who was "talkative and unconventional", besides being the inspiration for Emma, was also the inspiration for the character of Emily. The boarding school in the novel is set near where Penelope Farmer lived in London. However, it is based on the West Heath Girls' School in Sevenoaks, Kent, which she and her twin sister Judith attended in the 1950s. Elements in the book based on the school include the pillared front door, the glass verandah and the cedar tree, which still stands, as of 2020. Some of the characters there were based on real students of the time. The episode when Charlotte walks onto the glass verandah is based on a real event, when Penelope Farmer climbed on the glass verandah and broke it.