In the 1740s, over half of all London weddings were held at the Fleet (over 6500 per year) with a further thousand conducted at the May Fair Chapel.
By the late 17th century, provided that a couple exchanged vows and had some proof of this, then a marriage would be considered valid. Marriages by a form of ceremony conducted by an ordained clergyman, but without banns or licence, and generally not in a church or chapel, usually away from the parish of the bride or groom were termed clandestine marriages. The main appeal of clandestine marriages was seemingly for reasons of cost. Other reasons for their popularity included the avoidance of the need to obtain parental consent, and also to conceal embarrassing pregnancies.
Clandestine marriages began to grow in numbers from the middle of the seventeenth century. The authorities attempted to quell this growth by introducing three parliamentary acts between 1694 and 1696 which collectively regulated marriages, introduced marriage taxes and censured and suspended clergy found to be involved. These, however, only applied to marriage centres which came under the jurisdiction (or visitation) of the bishop of the diocese. These acts inadvertently gave a near monopoly to private marriage centres outside the bishop's visitation (e.g. prisons) and to clergymen (many of whom were prisoners) who had been dismissed or were in debt and who had nothing to lose by conducting clandestine, fee-paying marriages.
In 1711, Parliament passed legislation which included an attempt to deal with the problem of such clandestine marriages being conducted in prisons. A clause was included in the act to counter the loss of revenue (from non-payment of stamp duties) caused by clandestine marriages. The clause continued the imposition of fines for any person in 'holy orders' conducting a marriage but also introduced the same fine for any prison keeper who permitted such a marriage at his prison. While this prevented the marriages being performed inside the prisons, it did not prevent them being conducted in other locations in the vicinity of the prisons: e.g. the Liberties (or Rules) of the Fleet, or the Mint (for King's Bench Prison). On 25 March 1754, all clandestine marriages were made illegal by Lord Hardwicke's Marriage Act; although couples were still able to travel to other areas of the United Kingdom where the act did not apply: i.e. across the border into Scotland (e.g. Gretna Green), or to the Channel Islands and the Isle of Man.
Fleet Prison was primarily a debtors prison and stood on the east bank of the Fleet River in what is now Farringdon Street, London. The marriages performed at the Fleet involved all classes from London and the surrounding counties, but mainly catered for artisans, farmers, labourers and craftsmen from the poorer parishes of London, soldiers (including Chelsea Pensioners), and particularly sailors. King's Bench Prison was located on the east side of Borough High Street in Southwark. As with the Fleet, the majority of prisoners were debtors. Relatively few marriages were performed in the Prison itself, and by the 1740s, those marriages which had been performed in the Mint began to be held at the Fleet. The King's Bench and the Mint, because of their location, tended to attract a high proportion of couples from Kent and Surrey.
From the late 1720s, clandestine marriages commenced at May Fair, which eventually became only second to the Fleet in terms of notoriety for such marriages. Initially, May Fair marriages were performed at St George's Chapel, Curzon Street, Mayfair, near Hyde Park Corner then, from 1744, at a private dwelling house (the 'New' or 'Little Chapel') situated ten yards away from St George's Chapel. Whereas clandestine marriages performed at the Fleet and King's Bench prisons and surrounding areas tended to attract the working classes, the May Fair Chapel was used by professional classes and the aristocracy for marriages, including the Dukes of Cleveland and Hamilton, Lord Stanley, and Lord George Bentinck .
The need for a public record of the marriages meant that they were recorded in registers and some were produced as evidence in court cases. The registers of the Fleet were kept, for the most part, by the ministers (or their clerks) who performed the ceremonies, by self-appointed register-keepers, by the landlords of some of the houses where the ceremonies took place, and by persons who appear to have set up record offices at a later date and made copies of registers in the possession of others. It must be emphasised that the information in the Fleet documents (particularly those before 1714) should be treated with extreme caution as dates given are unreliable and names or indeed whole entries may be fictitious.