Question: When was John Spencer-Churchill, 10Th Duke Of Marlborough's mother born?
Sentence (from "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.
Relevant evidence: Yes