Flexner's research is mostly impeccable, painstaking, thorough, thoroughly documented and soundly applied. Usually she makes clear when she is posing a deduction or is filling in a gap with creative research or backing up an assumption by drawing from Wollstonecraft's fiction. For example, in describing Mary's paternal grandfather, Flexner surmises that he began as a tradesman with the ambition of becoming a gentleman (19–20). Although the other biographers— before and after the 1970s— mention that he was a weaver in the Spitalfields district and that he did well financially, they do not provide the kind of specifics that qualify these generalizations as does Flexner. She recounts that between 1753 and 1755 Edward Wollstonecraft leased land on Primrose Street in Spitalfields in London, an area that was the center of the silk- weaving industry (20). She found this information in the parish registers and poor- rate books of St. Botolph without Bishopsgate, records of which she located in the London Guildhall Library (287n1). On three blocks, he built houses from which rent would be collected from about 30 tenants for 60 years (20). The lease was to the Worshipful Company of Goldsmiths, and additional specifics are documented in Appendix A. Flexner recounts that the grandfather also owned shares in an East India Company merchant ship, Cruttenden, and she lists the voyages in Appendix A. Mary's brother inherited these shares. The evidence of the grandfather's purchase and development of land supports Flexner's assertions that he was not just a tradesman but also a man who was ambitious enough to invest his money in property that would place him and his heirs in the gentry.

When Flexner knew that she could not validate a claim from her research, she let the reader know it. Still, she did make some unsubstantiated claims, whether accurate or not, such as: “At some point Mr. Wollstonecraft had become so badly entangled financially that he used part of the money settled on his daughters to extricate himself. Mary's statement, in a letter to Jane Arden, is forthright: he took it, and she agreed to relinquish her share” (28). Surprisingly, Flexner neither cites the letter nor the source of the money.