Private letter from Lord Chief Justice Mansfield to the Duke of Atholl offering legal and tactical advice on how to respond to a letter from the Lords of the Treasury regarding Isle of Man affairs. Mansfield cautions against the Treasury's 'insidious' approach and recommends diplomatic communication with Grenville, comparing the situation to previous dealings with Walpole, Pelham, and Newcastle. Includes editorial suggestions for revising Atholl's draft response.