Alexander Montagu, 10th Duke of Manchester

His elder son, Sidney Arthur Robin George Drogo Montagu, succeeded him to the family titles. He died without issue, so his brother, Lord Angus Charles Drogo Montagu, became the 12th Duke.

At the time of his death in 1977 he was still listed in Who's Who as living at Kapsirowa, Hoey's Bridge, Kenya, but he died in London, after running through most of his inherited wealth.

On 7 February 1969 he married secondly, and without further issue, Elizabeth (née Fullerton) Coleman Crocker (1913–2007), daughter of Samuel Clyde Fullerton of Miami, Oklahoma. She had formerly been married to oil magnate George L. Coleman, then to William Willard Crocker, a son of William Henry Crocker and grandson of Charles Crocker.

During the 1950s, the Duke sold both the principal family seat, Kimbolton Castle, along with most of its contents, and Tandragee Castle in Ireland. By the 1960s, he had also sold most of the other landed estates in the British Isles which had come to him.

During the Second World War, Mandeville was posted to Ceylon, and in 1940 was appointed an Officer of the Order of the British Empire. After the end of the War he gave up living in England, moving to the Colony and Protectorate of Kenya in 1946. There, he farmed an estate of 10,000 acres. He succeeded to the Dukedom of Manchester on his father's death in February 1947.

In 1931, his parents were divorced, when his father was reported to be planning to marry an actress. In 1937, Helena Manchester married secondly The 10th Earl of Kintore.

On 5 May 1927 he married firstly, at Kimbolton Castle, Huntingdonshire, Nell Vere Stead (Ashfield, Sydney, Cumberland County, New South Wales, Australia, 1902 – 2 September 1966), daughter of Sydney Vere Stead (1861 – South Yarra, Melbourne, County of Bourke, Victoria, Australia, 1929), of Melbourne, and wife Jessie Lillian Dickinson (Newtown, Sydney, Cumberland County, New South Wales, Australia, 1873 – Armadale, Melbourne, County of Bourke, Victoria, Australia, 1926), by whom he had two sons:

From Dartmouth, Lord Mandeville was commissioned into the Royal Navy in 1919. He held the rank of Commander when he retired from the service in 1930.

Commander Alexander George Francis Drogo Montagu, 10th Duke of Manchester, OBE, RN (Tandragee Castle, 2 October 1902 – 23 November 1977), was a Royal Navy officer and British hereditary peer. From birth until February 1947, he was known by the courtesy title of Viscount Mandeville.

Born at Tandragee Castle in County Armagh, Ulster, in the north of Ireland on 2 October 1902, Lord Mandeville was the son of The 9th Duke of Manchester by his marriage to Helena Zimmerman, the only child of Eugene Zimmerman, of Cincinnati, Ohio, a railway president and major stockholder in Standard Oil. The wedding in November 1900 was kept secret from both families, and at first the Duke's mother did not believe reports of it. Queen Alexandra stood sponsor at his christening in the Chapel Royal (St. James's Palace) on 17 December 1902.