[13] He was a member of the prominent Standard Oil family, Mortimer is the maternal grandson of its president Henry Morgan Tilford.
[11] His paternal grandfather was Richard Mortimer, a real estate investor and member of Ward McAllister's "Four Hundred", purported to be an index of New York's best families.
[18] His grandmother, the widow of Henry Morgan Tilford, was known as "one of the reigning dowagers of Tuxedo Park" for four decades.
According to author Sally Bedell Smith, "her annual debutante dinners before the Autumn Ball determined which young women were approved for New York society.
His funeral was held in Tuxedo Park,[27] and speakers included his son and daughter, and Lewis Lapham, the editor.