John Winston Spencer-Churchill, 7th Duke of Marlborough KG PC (2 June 1822 – 4 July 1883), styled Earl of Sunderland from 1822 to 1840 and Marquess of Blandford from 1840 to 1857, was a British Conservative cabinet minister, politician, peer, and nobleman.
Portrait of John Spencer-Churchill with his parents and younger brother, by John Singer Sargent, 1905. He was born in London on 18 September 1897 as the first of two sons born to Charles Spencer-Churchill, 9th Duke of Marlborough and his first wife, the former Consuelo Vanderbilt , an American railroad heiress. 
Marlborough was born in England on 13 May 1844. He was the eldest son of John Spencer-Churchill, 7th Duke of Marlborough (1822–1883), who served as Lord Lieutenant of Ireland and Lord President of the Council, and Lady Frances Anne Emily Vane (1822–1899). He was the elder brother of Lord Randolph Churchill and the uncle of Winston Churchill.
El 28 de julio de 1683, Ana contrajo matrimonio, en el palacio de St. James de Londres, con el príncipe protestante Jorge de Dinamarca, hermano del rey Cristián V, una unión impopular debido a las inclinaciones francesas de Dinamarca, pero que fue de una gran felicidad doméstica, pues el príncipe y princesa eran de caracteres similares y preferían el retiro y la tranquilidad a la vida ...
Otra explicación es la que se refiere a John Churchill, el Duque de Marlborough (antepasado de Winston Churchill, el famoso amigo de Valentine Fleming, el padre de Ian Fleming) que utilizaba el código 00 para los espías que trabajaban para él en la Guerra de Sucesión Española (1701-1714).
Charles Richard John Spencer-Churchill, 9th Duke of Marlborough, KG, TD, PC (13 November 1871 – 30 June 1934), styled Earl of Sunderland until 1883 and Marquess of Blandford between 1883 and 1892, was a British soldier and Conservative politician, and a close friend of his first cousin Winston Churchill.
He inherited the Sunderland title from his older brother in 1729, becoming 5th Earl of Sunderland, and then the Marlborough title from his aunt Henrietta, 2nd Duchess of Marlborough in 1733. At that time, he handed over the Sunderland estates to his younger brother John , but he did not obtain Blenheim Palace until Sarah, the dowager duchess, died in 1744.