pipingrockclub

Phyllis Byrne was the sister of Mrs. Hamilton Fish Armstrong. The NY Times covered her debut and her wedding to Gardner Cox. Bronson Griscom appears to be the son of the U.S. "minister to Persia," who married Elizabeth Duer Bronson in 1901. Unfortunately all society coverage of them in the Times is from the 1930s (when they grew up!) and is behind a paywall.

Phyllis Byrne Cox gets a nice mention in Arthur Schlesinger's _A Life in the Twentieth Century_ (Houghton Mifflin 2000), on p. 237: "A couple who entered our lives in these years were Gardner Cox...and his lovely, gamine wife Phyllis Byrne Cox, one of the most enchanting and exasperating of women. Gardner was doing a portrait of my father, and he would bring Phyllis along to relax his subject during sittings. My father adored Phyllis, and so did I. She was a gifted pianist, and she was also an impulsive, outspoken, and ultimately poignant woman. Reared a Catholic, she had turned sharply against the Church and looked on those who remained in it with incredulity and scorn. She had had a fling in London with Ian Fleming, the creator of James Bond, I learned later... They gave excellent parties and provided Cambridge with a captivating taste of upper-class Bohemianism." Phyllis and Gardner Cox had three children, Benjamin, James, and Poppy; Phyllis was widowed when Gardner died in 1988.

I started an entry for the club: en.wikipedia.org/wiki/Piping_Rock_Club

The girl at left foreground, back to camera, is Sheila Byrne. Here's a Bain/LOC photo of her on a horse that day, at Piping Rock:

The whipped cream of New York society turned out in October, 1912, for the eleventh annual horse show at the Piping Rock Country Club, in Locust Valley, on the north shore of Long Island. A new clubhouse and stepped observation boxes had just been opened for their pleasure: Story in The New York Times, October 4, 1912: "SOCIETY AMATEURS IN THE SADDLE "Piping Rock Horse Show Attracts Hunting Set to Locust Valley Grounds" query.nytimes.com/mem/archive-free/pdf?res=9D06E1D6113BE6... Another story in The New York Times, October 5, 1912: "SOCIETY AIDS AT PIPING ROCK SHOW "Notable People View Amateur Horse Exhibition Amid Long Island Hills" query.nytimes.com/mem/archive-free/pdf?res=9506E6D7113AE6...

New-York tribune. (New York [N.Y.]), 29 Sept. 1918, image 21, bottom left chroniclingamerica.loc.gov/lccn/sn83030214/1918-09-29/ed-... confirms that Mrs. Henry C. Taylor competed successfully at the Piping Rock Horse Show, showing her horse Freize.

swanq: Thanks for finding out the rest of the story for this photo. We will add more details to the record.

According to New-York tribune., September 29, 1918, Image 21, bottom left chroniclingamerica.loc.gov/lccn/sn83030214/1918-09-29/ed-... her name is Corinne Poth. Her pony in harness was Cricket and they were tied for first place in Class 1. And it wasn't her only prize of the day.