He was the eldest son of Francis Spencer, 1st Baron Churchill, and Lady Frances FitzRoy.

Caroline Elizabeth Spencer, married Robert Dillon, 3rd Baron Clonbrock, and his brother, Sir Augustus Spencer, married Helen Maria Campbell (daughter of Lt.-Gen. Sir Archibald Campbell, 1st Baronet).

Sir Richard Wrottesley, 7th Baronet, Dean of Worcester) and Augustus FitzRoy, 3rd Duke of Grafton, who served as Prime Minister from October 1768 to January 1770.

[6] Together, Francis and Jane were the parents of one son:[3] He was a first cousin, twice removed, of Prime Minister and honorary citizen of the United States, Sir Winston Churchill.

He was also a third cousin, four times removed, of Diana, Princess of Wales, and is thus third cousin, five times removed, of her sons, Princes William, the Prince of Wales, and Harry, Duke of Sussex.