Queen Anne Royal Proclamation published on November 8, 1711. H.M. ordered quarantine installation on British ports due to Plague, a term used at that time for infectious diseases without knowledge of the causative agents.
Here the immediate cause was an epidemic that broke out in the Baltic Sea area.
The Act came after the Quarantine Act of 1710. Dr. K. Mayer did not described any document for 1711. He mentioned the 1721 Act.
I scan all four pages of the document.