Halfpenny Linda by Jean Nielsen (1963)
Even before she is off the plane the next day, Linda begins to have uneasy suspicions that while London is as different as can be from Los Angeles, she still hasn't solved her problems. Her aunt and uncle and two cousins, Icy, a year older, and Roger, two years younger than herself, are kind and welcoming, but their quiet reserve makes them strange to her. She soon finds out that the Lady Phillipa Grammar School for Girls is just that--there are no boys. Furthermore, the students wear unbecoming uniforms and take their lessons most seriously.
During her first difficult days, her main comforts are Mrs. Maxwell, her aunt's housekeeper, and Kath Hollister, a fellow schoolmate. Like Linda, Kath prefers to look on the lighter side of life, but still she is level-headed. In spite of Kath's good-natured guidance, Linda makes one mistake after another until finally a row with her unsympathetic Maths teacher sends her storming to the American Embassy, determined to borrow money to fly home.
An understanding embassy aide encourages her to stay and be an ambassador for her country, and after that things become somewhat easier for Linda. The old monuments of London cause her to take a real interest in the study of history. At a Christmas reception at the Embassy, she finally meets some boys--Andy and Jack, American students at Cambridge. She meets them again in Scotland where she is enjoying vacation with her newly met grandparents, and in Cornwall where she goes for the spring holidays. The high point comes when the boys extend invitations to Linda, Kath, and Icy, too, for May Week at Cambridge.
There are many more surprises and discoveries in store for Linda before her year in the British Isles in over--among them the realization that hard work results in very satisfying rewards. (from the inside flap)