William I of Württemberg
On 24 January 1816, in Saint Petersburg, he married his first cousin, Grand Duchess Catherine Pavlovna of Russia (1788–1819), daughter of Emperor Paul I of Russia (1754–1801) and Princess Sophie Dorothea of Württemberg (1759–1828). The couple had two children:
William Henry Wilkins
At Lund University in Sweden Wilkins discovered in 1897 the unpublished correspondence between Sophia Dorothea of Celle, the consort of George I, and her lover, Count Philip Christopher Königsmarck. This research, backed up from the archives of Hanover and elsewhere, led to "The Love of an Uncrowned Queen, Queen Sophie Dorothea, Consort of George I", which appeared in 2 vols. in 1900 (revised edit. 1903). His "Caroline the Illustrious, Queen Consort of George II" (2 vols. 1901; new edit. 1904), had less claim to originality. "A Queen of Tears" (2 vols. 1904), a biography of Caroline Matilda of Great Britain, Queen of Denmark and sister of George III of England, used research at Copenhagen and superseded the previous biography by Frederic Charles Lascelles Wraxall. For his last work, "Mrs. Fitzherbert and George IV" (1905, 2 vols.), Wilkins had access, by Edward VII's permission, for the first time to the Fitzherbert papers at Windsor Castle, besides papers belonging to Maria Fitzherbert's family. Wilkins argued for the marriage with George IV.