In 18th century England, the Anglican church had a lot of rules regarding marriage. One had to either post banns (announcements of intent to marry) for three weeks or purchase a license. Church officials could dictate when and where the marriage was to occur. There were residency requirements, age requirements, parental consent requirements, and periods in the church calendar when marriages were not allowed.
So what do you do if you want to avoid all of these rules and just get married, like, right now? Get married in a prison!
Most couples endured the rules of the established church but some preferred the easier solution of marrying outside the church, at institutions that regarded themselves as exempt from church law. These marriages were called "clandestine" marriages.
Prisons were popular choices for quick, easy ceremonies because there was a large number of clerics who were imprisoned for debt. Because of a legal quirk, jailed clergymen were beyond the reach of canon law. The income gained from such marriage ceremonies afforded them better accommodations in the areas adjoining but outside the prison walls. By the 1740s, about 6000 marriages a year, more than half of London marriages, were performed in the vicinity of London's notorious Fleet Prison, which was used primarily for debtors.
The government tried to regulate this practice by requiring prison keepers to demand banns or licenses before marriages could be performed. This only succeeded in pushing the ceremonies into taverns neighboring the prison. Finally, in 1754, the Hardwicke Act required formal church ceremonies for all marriages.
The Moore brothers' 6 x great-grandparents, Abraham Barefield and Mary Lingett, both of St. Sepulchre's parish, entered into a clandestine marriage on 23 March 1732, recorded in the marriage register of Fleet Prison.
The principal sources for this essay are:
"About London, England, Clandestine Marriage and Baptism Registers, 1667-1754," Ancestry.com (https://search.ancestry.com/search/db.aspx?dbid=5344 : viewed 20 Mar 2018).
"Fleet Marriage," Wikipedia.org (https://en.wikipedia.org/wiki/Fleet_Marriage : 6 Mar 2017).
"Fleet Prison," Wikipedia.org (https://en.wikipedia.org/wiki/Fleet_Prison : 11 Dec 2017).
Illustration, "Caricature of a Fleet Marriage, public domain, Wikipedia (https://commons.wikimedia.org/w/index.php?curid=238544 : July 2005); scanned from Robert Chambers' Book of Days, 1st edition, but likely derived from an earlier source.