In the so-called Screw Plot—a supposed conspiracy to assassinate Queen Anne during a Thanksgiving service in 1710—iron bolts were removed from the roof timbers of St. Paul’s Cathedral in order for the roof to collapse during the service. “The new cathedral was not then quite finished,” wrote John Noorthouck in 1773, “and it appeared upon inquiry that the missing of these iron pins was owing to the neglect of the workmen, who supposed the timbers were sufficiently fastened without them.”