I went into Slammerkin knowing essentially nothing about it, other than that it was a historical novel set in 18th century England and had a female protagonist. I endorse this method of encounter, and will endeavor to not spoil the book for you.
It purports, in the afterword, to be based on a true story, but the details of the events referenced are largely unknown, and the motivations of the persons involved still less so. The canvas thus prepared for Emma Donoghue's perceptive reimagining, we are drawn into the achingly common story of Mary Saunders's "fall": A mere girl, tarnished forever by sexual impurity, embraces the relative freedom offered by a life of prostitution. After some years of hard and fast living, her options and friends dwindling, Mary makes a daring choice: To impersonate herself, as the girl she would have been, and return to her mother's village on the Welsh border to make a living as a seamstress. A happy ending for Mary is almost within reach, but her emotional ties to the independence of her former life, coupled with the greed and malice of a former client, make clear that Mary is not destined to live a simple life of sewing and children. The strongest aspect of the novel is in Donoghue's characterization of Mary, who does not just have weaknesses, but demonstrates them in organic and believable ways. The ending, though, comes abruptly and does not follow as smoothly from Mary's motivations as her prior conduct. Nevertheless, recommended for historical fiction readers.