The American branch of Diana, Princess of Wales’s ancestry reaches back to the great Puritan migration of the seventeenth century, when English settlers established enduring communities across New England. Among the families who arrived during that period were John Cogswell and his wife, Elizabeth Thompson, whose passage from Wiltshire to Massachusetts formed an early link in a lineage that would, centuries later, return unexpectedly to Britain.

John Cogswell (1592–1669), a prosperous merchant from Westbury Leigh, Wiltshire, sailed for Massachusetts in 1635 aboard the Angel Gabriel. When the ship was wrecked in a violent storm off the Maine coast, Cogswell and his family survived but lost substantial property and possessions. They eventually continued south to Ipswich in the Massachusetts Bay Colony, where Cogswell became a substantial landowner and a respected figure in local affairs. Elizabeth Thompson, daughter of the Rev. William Thompson of Westbury, shared the hazards of the voyage and settlement and helped establish the family in New England.

Over succeeding generations, branches of the Cogswell descendants became connected with other established New England families, including the Strong, Dwight, Huntington, Denison, and Alsop lines. These were families deeply involved in the civic, religious, and intellectual life of colonial New England. The later ancestry included descendants of such early colonial figures as Elder John Strong of Northampton, as well as members of the Dwight and Huntington families, whose names became closely associated with the development of Massachusetts and Connecticut.

By the nineteenth century, this line had reached Franklin H. Work (1819–1911), a New York stockbroker and financier associated with Cornelius Vanderbilt. His daughter, Frances Ellen Work (1857–1947), inherited immense wealth and social prominence, becoming a notable figure of the Gilded Age. Raised amid the worlds of Manhattan and Newport, she represented the era’s union of American fortune and European social ambition.

In 1880, Frances married James Boothby Burke Roche, an Irish aristocrat who later succeeded as the 3rd Baron Fermoy. Their marriage carried her American ancestry back across the Atlantic and into the British and Irish aristocracy. Their son, Edmund Maurice Burke Roche, later the 4th Baron Fermoy, was the maternal grandfather of Diana, Princess of Wales.

The line that had entered New England with Puritan settlers in the seventeenth century thus returned to Britain more than two centuries later through the marriage of an American heiress to an Irish peer. Through Frances Ellen Work, the colonial inheritance associated with the Cogswell, Thompson, Strong, Dwight, Huntington, Denison, and Alsop families became part of the ancestry of Diana, Princess of Wales.