Mr. Churchill's Secretary by Susan Elia MacNeal

A young British woman, raised in America, has returned to London on family business. When war breaks out, she joins Churchill's staff as a typist. My initial impression was that the book was intended as an historical novel because early on the author includes many of Churchill's speeches and devotes some time to describing the work in his office. But the book is really a combination of historical novel and mystery and doesn't really measure up as either one. The characters are sketches to a large degree and the plot twists and turns are unbelievable and confusing. Our heroine encounters Nazi spies, IRA terrorists, long lost relatives, secrets involving her life which are being kept from her by British Intelligence. The story builds rather slowly but the last part heads in to a wild ride of crazy plot turns and unbelievable rescues.