The Gypsy Crown by Kate Forsyth
Emilia Finch and her cousin Luka are gypsies. For them, that means they live a strongly traditional life, rich with story, music, dance, and magic, governed by the laws of the clan and the ways of the road. To the repressive Puritanical government of 17th century England, however, the gypsies are thieving, fortune-telling vagrants who are most likely allies of the devil. While the Finches have managed to steer clear of trouble, it finds them when they decide to raise dowry money for one of their daughters, by performing in Kingston square one ill-fated market day. A series of terrible events lands the family in jail, charged with murder. Only Emilia and Luka manage to escape, promising to bring back help and free them.