The Lady Disguised — Elizabeth Mansfield

When the Honorable eight-year-old Stanley Farrington vanished, his sister Ada set out to find him. Disguising herself in boys' clothing, she started her perilous search in a nearby gypsy camp, ending it in the splendid drawing rooms of the London ton.

Now, Ada Farrington is in a proper muddle. Derek Rutledge, the man she loved, thought she was a boy. As did Derek's daunting mother, the ton's most indefatigable matchmaker!... Hope and heartbreak warred in Ada's proud spirit. For if she kept her secret, she would lose her love. Yet if she revealed the truth, she would be a mere country wildflower amid a thousand hothouse blossoms! Ada was determined to win this complicated game of romance, for its victory was the sweetest reward of all ...