When about seventeen this "Duchess of Lancaster" _in petto_ came to London, and made the acquaintance of John Thomas Serres, proprietor of the Coburg Theatre, and son of a royal academician. Upon the 1st of September, 1792, this descendant of the sovereigns of England and Poland was married to Mr. Serres, but, as might be anticipated, the union was not a very happy one, and in 1803 a separation took place. Of the four children who were issue of this marriage, two daughters grew up, one of whom, Lavinia, born in 1797, remained with her mother, whilst the other went with her father. Mrs. Serres, who became an author and artist, and published a book to prove that the _Letters of Junius_ were written by Dr. James Wilmot, would appear to have been somewhat crazed, at least towards the latter part of her life. She assumed the title of Princess of Cumberland, and brought up her daughter Lavinia in the belief that she was of royal lineage. Dr. Wilmot, who died in 1807, at the advanced age of eighty-five, was supposed to have left his daughter the following remarkable document:-- "MY DEAR OLIVE,--As the undoubted heir of Augustus, King of Poland, your rights will find aid of the sovereigns that you are allied to by blood, should the family of your father act unjustly; but may the great Disposer of all things direct otherwise. The Princess of Poland, your grandmother, I made my lawful wife, and I do solemnly attest that you are the last of that illustrious blood. May the Almighty guide you to all your distinctions of birth! Mine has been a life of trial, but not of crime!" J. WILMOT. "_January_ 1791."