His Highness Prince Alastair Arthur of Connaught was born in London, the only child of Prince Arthur of Connaught and his wife, Princess Alexandra, Duchess of Fife. Under settled practice since 1714, all legitimate children and male-line grandchildren of a British sovereign were titled Prince or Princess of Great Britain and Ireland with the style Royal Highness, while legitimate great grandchildren in the male line were titled Prince or Princess of Great Britain and Ireland with the style of Highness. In Letters Patent dated November 20, 1917, King George V restricted the titles of Prince or Princess and the style of Royal Highness to the children of the sovereign, the children of the sovereign's sons, and the eldest living son of the eldest son of the Prince of Wales. It further stated all titles of "the grandchildren of the sons of any such Sovereign in the direct male line (save only the eldest living son of the eldest son of the Prince of Wales) shall have the style and title enjoyed by the children of Dukes."1 At that point, the three year-old became known as Alastair Arthur Windsor, Earl of MacDuff. Although third in line to the dukedom of Connaught and Strathearn at the time of his birth, he was the heir apparent to his mother's dukedom of Fife. Therefore, he used his mother's secondary peerage as a courtesy title.
The Earl of MacDuff received his education at Bryanston and at Sandhurst. In January 1935, he received a commission as a second lieutenant in the Royal Scot Greys (2nd Dragoon), the same regiment in which his father served. He was posted to Egypt in 1936 and remained there until his transfer to Canada in 1939. He received a promotion to first lieutenant in July 1939. The Earl of MacDuff served as an aide-de-camp to his uncle, the Earl of Athlone, then the governor-general of Canada. His father, Prince Arthur of Connaught, died on September 12, 1938. Therefore, when his grandfather died on January 16, 1942, he succeeded as 2nd Duke of Connaught and Strathearn and Earl of Sussex.
The Duke of Connaught died at Government House in Ottawa, where he had been a guest of the Earl of Athlone and Prince Alice, Countess of Athlone. His ashes were interred at Mar Lodge Chapel, Braemar, Aberdeenshire. Upon his death, the dukedom of Connaught and Strathearn became extinct. His first cousin, James Carnegie (September 23, 1929-), succeeded as 3rd Duke of Fife and Earl of MacDuff, upon Princess Alexandra's death on February 26, 1959.
Footnote
1 George V's Letters Patent of November 30, 1917 also stated that "the titles of Royal Highness, Highness or Serene Highness, and the titular dignity of Prince and Princess shall cease except those titles already granted and remaining unrevoked." In an article in the 1963 edition of Burkes' Peerage and Baronage, Philip M. Thomas argues that "the denial of the Princely title to him [Prince Alastair] was erroneous and unjust" because his title was already granted and remained unrevoked.
Sources
Marlene A. Eilers, Queen Victoria's Descendants (New York: Atlantic International Publications, 1987).
"Obituary: The Duke of Connaught," The Times, April 27, 1943, p. 6.
Philip M. Thomas, "The Princes of Great Britain," Burke's Peerage and Baronage, 1963 edition, p. xxix