Consuelo Vanderbilt
Consuelo Vanderbilt Balsan (formerly Consuelo Spencer-Churchill, Duchess of Marlborough; born Consuelo Vanderbilt; 2 March 1877 – 6 December 1964) was a member of the prominent American Vanderbilt family.
Her marriage to The 9th Duke of Marlborough has become an emblem of the socially advantageous, but loveless, marriages common during the Gilded Age.
James Spencer-Churchill, 12th Duke of Marlborough
Charles James Spencer- Churchill, 12th Duke of Marlborough( born 24 November 1955), styled Earl of Sunderland until March 1972 and Marquess of Blandford until October 2014, and often known as Jamie Blandford or Jamie Marlborough, is an English peer and the current Duke of Marlborough.
He is the eldest surviving son of the 11th Duke of Marlborough and his first wife, Susan Mary Hornby.
As a member of the Spencer family, he is a distant relative of the war- time Conservative Prime Minister Sir Winston Churchill and of Diana, Princess of Wales, born Lady Diana Spencer.
He is also a stepbrother of Christina Onassis by the second marriage of his father with Athina Livanos.
Mary Osborne, Duchess of Leeds
Mary Osborne, Duchess of Leeds( 1723 – 3 August 1764), born Lady Mary Godolphin, was a daughter of Henrietta Godolphin," née" Churchill, 2nd Duchess of Marlborough, and Francis Godolphin, 2nd Earl of Godolphin, making her granddaughter to the powerful government trio during the reign of Queen Anne of Great Britain: the famous general and politician John Churchill, 1st Duke of Marlborough, and his wife Sarah, Duchess of Marlborough, through her mother; and Sidney Godolphin, 1st Earl of Godolphin, through her father.
Lady Mary was considered to be the illegitimate child of the famous playwright William Congreve, with whom Henrietta, Duchess of Marlborough, was having a long- term relationship.
She was, however, recognised by Francis as his own daughter, and was raised by him with the other Godolphin children.
Despite this, gossip spread rapidly about Lady Mary's paternity, and her maternal grandmother did not recognise her until 1740, when the two reconciled their differences.
It was at this time that Sarah, Dowager Duchess of Marlborough, arranged Lady Mary's marriage to Thomas Osborne, 4th Duke of Leeds; they were married on 26 June 1740.
They had one surviving child, Francis Godolphin Osborne( styled Marquess of Carmarthen, later 5th Duke of Leeds and Secretary of State for Foreign Affairs), who was born on 29 January 1751.
Mary, Duchess of Leeds, died in 1764, aged 41.
Harriet Pelham-Holles, Duchess of Newcastle-upon-Tyne
Henrietta" Harriet" Pelham- Holles, Duchess of Newcastle- upon- Tyne( 1701 – 17 July 1776) was the wife of the British statesman and Prime Minister Thomas Pelham- Holles, 1st Duke of Newcastle- upon- Tyne.
She was the daughter of Francis Godolphin, 2nd Earl of Godolphin and Lady Henrietta Churchill, 2nd Duchess of Marlborough and the granddaughter of Sidney Godolphin, 1st Earl of Godolphin and John Churchill, 1st Duke of Marlborough and Sarah Churchill, Duchess of Marlborough.
Until her marriage she was known as Lady Harriet Godolphin.
Like her husband, she was a devoted Whig and supporter of the Hanoverian succession.
They married on 2 April 1717.
During the 1720s, they became famous for throwing sumptuous parties, a tradition that continued for several decades.
These were attended even by her husband's political opponents.
Caroline Spencer, Duchess of Marlborough
Caroline Spencer, Duchess of Marlborough( 13 January 1743 – 26 November 1811), formerly Lady Caroline Russell, was the wife of George Spencer, 4th Duke of Marlborough.
Minamoto no Chikako
She was the mother of Prince Morinaga.
Anne Stewart, Countess of Galloway
Anne Stewart, Countess of Galloway (1743 – 8 January 1830), formerly Anne Dashwood, was the wife of John Stewart, 7th Earl of Galloway.
Anne Dashwood was born at Kirtlington Park, Oxfordshire, the family home of her parents Sir James Dashwood, 2nd Baronet, and his wife, the former Elizabeth Spencer.
On 13 June 1764, she married the future earl, when he was an MP and heir to his father's earldom.
His first wife, Lady Charlotte Greville, had died in 1763, leaving him with no living children.
In the year of their marriage, Sir Joshua Reynolds painted Anne in the guise of a shepherdess; the portrait is now held by the Metropolitan Museum of Art, New York.
They had sixteen children:
John Stewart inherited the earldom of Galloway in 1773, making his wife a countess.
He died in 1806, at which point she became Dowager Countess of Galloway.
Two years later, a court case ensued over a trust deed set up by the earl in 1804, whereby the trustees were authorised to sell property and appoint additional trustees.
The dowager countess having declined to accept nomination as a trustee, a Mr Forbes, who had purchased part of the estate, took the trustees to the Court of Session, claiming he was not bound by the terms of the purchase; the Court of Session found against him.
The countess died, aged 86, at Davies Street, Westminster, London.
Robert Spencer, 4th Earl of Sunderland
Robert Spencer, 4th Earl of Sunderland( 24 October 1701 – 15 September 1729) was a British peer from the Spencer family, the son of the Whig politician, Charles Spencer, 3rd Earl of Sunderland.
His mother was Lady Anne Churchill, the daughter of John Churchill, 1st Duke of Marlborough and Sarah Churchill, Duchess of Marlborough.
Known as Lord Spencer between 1702 and 1722, he succeeded to the Earldom after his father's death in 1722, but died in 1729 with no children.
Therefore, his brother, Charles, became 5th Earl of Sunderland, and subsequently 3rd Duke of Marlborough after the death of his aunt, Henrietta Godolphin(" née" Churchill), 2nd Duchess of Marlborough.
Susan Spencer-Churchill, Duchess of Marlborough
Susan Spencer-Churchill, Duchess of Marlborough (10 April 1767 – 2 April 1841), formerly Lady Susan Stewart, was the wife of George Spencer-Churchill, 5th Duke of Marlborough.
Lady Susan Stewart was the daughter of John Stewart, 7th Earl of Galloway, and his second wife, the former Anne Dashwood.
She married the future duke on 15 September 1791, when he was styled Marquess of Blandford.
They were married at her father's house in St James's Square, London, by the Archbishop of Canterbury, John Moore.
They had four children:
In 1817 the marquess inherited the dukedom from his father, George Spencer, 4th Duke of Marlborough, at which point his wife became Duchess of Marlborough.
The duchess died at her house in Park Lane, London, aged 73.
In the previous year two of her sons, Charles and Henry John, had died, along with Charles's wife and her husband the duke himself.
She was buried in the chapel of Blenheim Palace.
Gladys Spencer-Churchill, Duchess of Marlborough
Gladys Marie Spencer-Churchill, Duchess of Marlborough ("née" Deacon; 7 February 1881 – 13 October 1977) was a French American aristocrat and socialite.
She was the mistress and later the second wife of Charles Spencer-Churchill, 9th Duke of Marlborough.

Question: What is the place of birth of Susan Spencer-Churchill, Duchess Of Marlborough's mother?
Answer: Oxfordshire