Courtenay was baptized on 30 August 1768, the fourth of 14 children and was known as "Kitty" to family and friends. On his father's death he became The 3rd Viscount Courtenay of Powderham. With his new title and wealth, the young Lord Courtenay led an excessively flamboyant lifestyle. He was responsible for the addition of a new Music Room at Powderham Castle, designed by James Wyatt, which included a carpet made by the newly formed Axminster Carpet Company.
Homosexuality
Courtenay was in his time considered a notorious homosexual. His near neighbour and contemporary Rev. John Swete of Oxton House, Kenton in Devon, wrote of him in veiled terms as follows in connection with a discussion of the Parsonage House of the parish of Powderham: Courtenay was described as follows by the genealogist Thomas Christopher Banks in a letter to Lord ChancellorBrougham, who was an active force behind the decisionof the House of Lords to revive the Earldom in his favour:
Relationship with William Beckford
As a youth, 'Kitty' Courtenay was sometimes named by contemporaries as the most beautiful boy in England. Courtenay was homosexual and became infamous for his affair with William Beckford; they had met when Courtenay was ten but Beckford, only 8 years his senior, was already a wealthy art collector and sugar plantation owner. In the autumn of 1784, a houseguest overheard an argument between the then 18-year-old Hon. William Courtenay and Beckford over a note of Courtenay's. There is no record of what the note said, but the houseguest said that Beckford's response on reading it was that he entered Courtenay's room and "horsewhipped him, which created a noise, and the door being opened, Courtenay was discovered in his shirt, and Beckford in some posture or other — Strange story." Beckford was subsequently hounded out of polite British society when his letters to Courtenay were intercepted by Courtenay's uncle, Lord Loughborough, who then publicised the affair in the newspapers.
Later life
Courtenay was forced to live abroad, and lived in the United States where he owned a property on the Hudson River in New York, and later in France, in Paris and in Draveil where he owned a castle. He died unmarried, and fathered no known children. In 1831, as The 3rd Viscount Courtenay, he successfully petitioned to revive the title of Earl of Devon for the head of the Courtenay family, that title having been dormant since 1556, and so became the 9th Earl. He died on 26 May 1835 at age 66 in Paris due to natural causes. He was loved by his tenants, who insisted that he be buried in stately fashion. He was buried on 12 June 1835 in Powderham.