He became the 6th Baron Plunket, of Newtown in the County of Cork, on the death of his father on 24 January 1920.
On 4 December 1922, he married Dorothée Mabel Barnato (née Lewis), widow of Captain Jack Barnato and the illegitimate daughter of actress Fannie Ward and The 7th Marquess of Londonderry.
As guests of publicist William Randolph Hearst, Lord Plunket, his wife and their travelling companion, James Lawrence, a son of Sir Walter Lawrence of London, boarded a plane owned by Hearst's San Francisco and Los Angeles newspapers.
In the coastal fog surrounding the airstrip on the ranch, the pilot overshot the field by nearly a mile and a half.
[1] One wing struck the ground, causing the plane to burst into flames and crash.