Penn was the grandson of William Penn, founder of Pennsylvania; his father dressed like a Quaker until his later days, when he ‘became a Protestant’ and received the Sacrament before he died.
Penn, whose brother became private secretary to Lord Hobart at the War Office in September 1801, came into Parliament as a paying guest of the Duke of Leeds at Helston in 1802. He supported Addington at first, but voted against administration with Pitt and Fox on three crucial defence motions that brought down Addington, 15 Mar., 23, 25 Apr. 1804. Penn went on to support Pitt, who saw to it that he obtained the governorship of Portland and the command of the local militia. In April 1805 he vacated his seat, by an arrangement with the new patron of Helston, (Sir) Christopher Hawkins.
Penn was never again in Parliament: he devoted himself to belles lettres and projects of social utility such as the Outinian Society (1817), which he founded to promote domestic happiness among married people. He was president and editor of the society, which met first at his town house and later at Stoke Park. ‘Mr Penn raised many a smile by his employing more than one lecturer gravely to persuade youth of both sexes to enter into the holy bonds of matrimony’:
