Mask of Fortune (a Regency Romance‪)‬

Dermot, Earl of Heronforth, reluctantly accepts the obligation of his dead brother to bear-lead young Bobby Blain around Town. But Bobby  turns out to be Roberta, not at all what he expected. Bobby, already courted by two suitors at home, needs to be in London to attempt to clear her father's name of cheating at cards. Her discoveries lead to a kidnapping and a daring pursuit. Regency Romance by Sally James; originally published by Hale [UK]