The title of Viscount Rassendyll cannot have been conferred before 1440.
The title of Earl of Burlesdon was conferred upon Robert Rassendyll, 18th Viscount Rassendyll, during the seventeenth century.
In 1733, Prince Rudolf Elphberg, son of King Henry the Lion of Ruritania, embarked on an affair with Amelia, Countess of Burlesdon. Her husband (and distant cousin) James, the 5th Earl, fought the Prince in a duel but suffered a chill as a result of injuries sustained, and died six months later. Acknowledged as his heir was his posthumous son the 6th Earl, but whose bright red hair, long nose and blue eyes proclaimed him the natural son of Prince Rudolf (later King Rudolf III). Subsequently, generations of Rassendylls would either be dark-headed Rassendylls or red-headed Elphburgs in form and character.
The protagonist of The Prisoner of Zenda and Rupert of Hentzau by Anthony Hope is the Hon. Rudolf Rassendyll, younger brother of Robert, Earl of Burlesdon. Their cousin Ralph is the founder of an American branch of the family.
Information about the family may be found in the Hope novels, in Tarzan Alive and Doc Savage: His Apocalyptic Life, and in various pastiches of Hope's works.