Prince Alastair lost his title of Prince of Great Britain and Ireland under the letters patent of 1917 that changed the Royal Family's surname to Windsor; and abolished the entitlement of great-grandchildren of a sovereign the title Prince. As such Prince Alastair was then known as the Earl of Mcduff, a courtsey title as his mother was Duchess (in her own right) of Fife.
In 1942, on the death of his grandfather, Prince Arthur, Duke of Connaught, Alastair became the 2nd Duke of Connaught.
Alastair served in the armed forces, as a lieutenant in the The Royal Scots Greys regiment.
Alastair died on active service in Canada.