Blow Out the Moon at a Friends of the Library sale. The book is shown on the cover as a novel, in some places it's described as an autobiography, but it is actually a memoir of Libby Koponen's 18 month stay at a boarding school in England in the 1950s.
Her father was working for J. Walter Thompson and insisted on taking his family with him when he was transferred to London for a short period. The family were obviously well off as they board a cruise vessel for the trip across the Atlantic. I lived in England as a child and later moved to the U.S. and I found that my experiences were in reverse to hers. She had to learn how to hold a knife and fork while eating. I, on the other hand, couldn't get used to holding food in my hands and tried to eat a Taco with a knife and fork! She refused to sing God Save the Queen which she felt was disloyal to America and remarked that the tune was the same as My Country 'Tis of Thee. I, on the other hand, had no idea what the Pledge of Allegiance was.
School was a challenge as she had only used a pencil in America and a fountain pen was foreign to her (most English schoolgirls during that period had a constant ink stain on their finger). In the afternoons everyone was given a small bottle of milk to drink (I remember that most of the time these were left out in the sun and tasted horrible). She was also surprised that there was nothing in the history books about the American Revolution. During church services, she thought "God seemed so English" and didn't believe there was "someone in the sky who cared about everyone."
Her first story, The Richardsons, wasn't well received by the headmistress as it inferred that the Germans had occupied England which the headmistress was quick to point out had never happened - England had never been invaded by a foreign army. The headmistress went on to quote a verse in Shakespear's Richard II where England's surrounding sea is considered a moat.
Libby's life was one of privilege, gaining entrance to a prestigious boarding school, (Sibton Park) travel by cruise ship, and after their time in England, the family toured Europe for two months before returning home.