The Flowering Thorn — Margery Sharp

A Jazz Age socialite impulsively adopts an orphaned boy in this humorous, heartwarming tale
 
In 1929 London, twenty-eight-year-old Lesley Frewen lives a privileged, cultured life. But one thing is missing: love. When her aunt's female companion suddenly dies, leaving behind a young son, Lesley decides on a whim to adopt four-year-old Patrick -- though she doesn't have any particular affection for children.
 
As soon as Patrick moves in with her, Lesley gets to work using her connections to enroll him in the finest boys' school. But she quickly discovers London is no place to raise a child, and they relocate to the tiny village of High Westover.
 
The hamlet boasts a post office, a church, and a vicarage. There's an apple orchard and children for Patrick to play with. However, the country comes with its own set of daunting challenges: Lesley can't imagine how she'll entertain her friends there! But ultimately life with Patrick will change her, bringing out her capacity to love and showing her the difference between pleasure and happiness.