British government department which became central to Manx financial and administrative affairs during the negotiations for Revestment and after the Crown purchase of 1765.

Treasury involvement increased as British ministers sought to suppress the running trade. The department received memorials from merchants and customs officials describing the effect of Manx imports on British and Irish revenue. It also became one of the principal channels through which proposals for purchasing the Island from the Atholls were considered.

The negotiations involved questions well beyond the price of the lordship. Treasury papers dealt with the value of customs revenues, the rights retained by the Atholl family, compensation, the regulation of Manx trade and the administrative machinery required after purchase.

Following Revestment, Manx customs and revenue became matters of direct Treasury concern. Officials in the Island submitted reports and proposals on duties, permitted imports, port administration and revenue collection. William Lutwidge’s proposals for regulating Manx trade were among the papers sent into this system.

Treasury oversight did not mean that the Island ceased to possess its own legislature or courts. Its role was principally financial and administrative, especially where Manx trade affected British customs revenue or where expenditure required approval from London.

The department also appears repeatedly in later disputes over salaries, public expenditure and the costs of Crown administration in Mann.