The Sun (7 Dec 1919) Britain's Great Matrimonial Catch, Heir to Vanderbilt Millions, Enggaged. Marquis of Blandford, Son of Consuelo, Duchess of Marlborough, to wed the Hon. Alexandra Cadogan, heiress of Meux-Fortune attained by her parents through their kindliness to the sporting duchess, Susan. Consuelo Vanderbilt. John Spencer-Churchill, 10th Duke of Marlborough. 9th Duke of Marlborough.