Sources
Source 1: The Diary of Samuel Pepys
Samuel Pepys, an important figure in the Navy Office in London, kept a fascinating diary of his life for the years 1660-1669. He lived through the Great Plague, and in his Diary gave us the best, most graphic eyewitness account of this dreadful event. The Diary was a crucial source for Plague Searchers.

3. J.K. Rowling’s books have Muggles, while “Plague Searchers” has Muggletonians (who really existed), and includes some of their Divine Songs.
Religion figured large in the 17th century, and so it does in “Plague Searchers.” Henry VIII’s split from the Church of Rome in the previous century was still a source of conflict, and Henry’s Church of England was also intolerant of the many protestant dissenters and non-conformists who flourished under Oliver Cromwell. Of the numerous small protestant churches, the Muggletonians were an obscure but long-lived sect. Founded in 1651 by two London tailors, John Reeve and Lodowicke Muggleton, the Muggletonians continued to exist in comfortable obscurity until the death of the last Muggletonian, Philip Noakes, in 1979.
They had their own book of Divine Songs, sung to popular tunes of the day. Here is the cover of the 1829 edition.

Source 2: This is a 1764 printing of the psalms I bought as part of my research
The congregation singing the psalms as songs put into verse by Sternhold and Hopkins was a vital part of parish worship in the 17th century.
