By the mid-eighteenth century, the common methods in the United Kingdom for dealing with the insane were either to keep them in the family home, or to put them in a "madhouse", which was simply a private house whose proprietor was paid to detain their residents, and ran it as a commercial concern with little or no medical involvement.

[1] In a case in the mid-1750s, a woman came to suspect that her son-in-law had committed his wife to a madhouse in Hoxton; with the aid of a justice of the peace, she secured the release of her daughter after obtaining a confession from the husband.

His initial application to Lord Mansfield for a writ of habeas corpus was rejected because he was not a relative and so had no standing, but the judge arranged for a doctor to visit the house and speak to the woman.

[2] A Select Committee of the House of Commons, chaired by Thomas Townshend, was set up in 1763 to study the problem of unlawful detention in private madhouses and focused on the Hawley case.

This was, the committee stated, a common situation; they noted that a number of similar cases could have been studied, and they recommended that some form of legislative intervention was needed.

[11] The Act took effect on 20 November 1774, six months after receiving royal assent, and was originally stated to remain in force for five years and then until the end of the next parliamentary session.