Perfecting Fiona

the long version

"Amy and Effy Tribble place an advertisement in the Morning Post and hire themselves out as chaperones to prepare difficult young misses for marriage, educating them in their school for Manners. Fiona has been sent to them by her guardians as a last resort, for at nineteen the beautiful and wealthy Scottish heiress still has no prospect of a suitable marriage. The Tribbles are puzzled, however, by their charge's demure perfection, until they take her to her first ball - and discover she is an incorrigible flirt!"--Publisher's description.