The Boultons had three daughters in the early 1750s, but all died in infancy. Mary Boulton's health deteriorated, and she died in August 1759. Not long after her death Boulton began to woo her sister Anne. Marriage with a deceased wife's sister was forbidden by ecclesiastical law, though permitted by common law. Nonetheless, they married on 25 June 1760 at St. Mary's Church, Rotherhithe. Eric Delieb, who wrote a book on Boulton's silver, with a biographical sketch, suggests that the marriage celebrant, Rev. James Penfold, an impoverished curate, was probably bribed. Boulton later advised another man who was seeking to wed his late wife's sister: "I advise you to say nothing of your intentions but to go quickly and snugly to Scotland or some obscure corner of London, suppose Wapping, and there take lodgings to make yourself a parishioner. When the month is expired and the Law fulfilled, live and be happy ... I recommend silence, secrecy, and Scotland."