While we're on the topic of
Blenheim Palace 
For anyone who may be interested here's a bit of fun-trivia about the family's history...(very condensed version)
No doubt the family name is very familiar to some, which has probably caused a bit of confusion.
Blenheim being the family home of the
Duke of Marlborough, the most famous in recent history being
Sir Winston Churchill, who was born there.
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Now bringing us rightly On-Topic for
this thread -
Sir Winston was also a relative of
Diana, Princess of Wales...
Spencer family history
The House was founded in the 15th century by Henry Spencer, from whom all members descend...
The senior branch of the Spencers (later known as the Spencer-Churchill family) is currently represented by His Grace Jamie Spencer-Churchill, 12th Duke of Marlborough, direct descendant via the eldest son male-line of Sir John Spencer, while the cadet branch of the family, the Spencers of Althorp who descends via the male-line from the younger son of the is represented by The Right Honorable Charles Spencer, 9th Earl Spencer.
John Spencer, 1st Earl Spencer, by Thomas Gainsborough
Rise to wealth
A close relative of Henry Spencer was John Spencer, who in 1469 had become trustee of Wormleighton in Warwickshire and a tenant at Althorp in Northamptonshire in 1486. His nephew, Sir John Spencer made a living by trading in livestock and eventually saved enough money to purchase both the Wormleighton and Althorp lands. Wormleighton in 1506, then in 1508, the estate of Althorp with its moated house and several hundred acres of farmland. He had grazed sheep here from the 1480s. Impressed by the quality of the land, he bought it and rebuilt the house...
Spencer, of Althorp House
... putting down roots at Althorp, Spencer provided what was to become a home for the next 19 generations. In 1519 he was knighted by King Henry VIII, he is now buried in the family chapel at Great Brington.
After the death of his elder brother, Robert, in 1729, Charles Spencer had already inherited his titles as well as the Spencer family estates. In 1733, he succeeded to the Churchill family estates and titles and became the 3rd Duke of Marlborough, while the Spencer estates (including Althorp) passed to his younger brother John. 
Spencer family