People and Us Weekly magazines each said they had independently confirmed reports that the 60-year-old Cook, of Sag Harbor with an office in Water Mill, had proposed to Jancou, 21, in Santorini, Greece, on Sept. 15. The six-carat diamond engagement ring was designed by Glenn Bradford Fine Jewelry of Port Washington and Southampton.
"Glenn designed a stunning 3 stone ring for Peter Cook's finance Alba Jancou," the firm posted on its Facebook page Tuesday. "We feel blessed to have been a part of this beautiful life moment. We wish them every happiness."
Cook, who was Brinkley's fourth husband with a 1996 Hamptons marriage and a 2008 divorce, attended numerous events with Jancou over the summer, including the East Hampton Library Authors Night, the East Hampton Artists and Writers Charity Softball Game at Herrick Park, and the Hampton Classic Horse Show Grand Prix in Bridgehampton.
Jancou is a psychology student at The New School, specializing in the field of social research.
Cook had no comment when contacted by Newsday. Neither he nor Jancou have commented on social media.
This will be Cook's third marriage. He wed Suzanne Shaw on Valentine's Day 2012. The couple eventually divorced.
Cook had adopted Jack Taubman, now Jack Brinkley-Cook, Brinkley's son with third husband Ricky Taubman. The child was a year old when Cook and Brinkley married. The couple had daughter Sailor on July 2, 1998. Neither of the siblings has commented on social media.
On Sept. 25, Cook had posted on Instagram to congratulate his daughter for competing on "Dancing With the Stars" this season. Alongside a media image for the show, with Sailor Brinkley-Cook and professional ballroom dancer Val Chmerkovskiy, he wrote, "Happy belated national daughters day! I’m proud of the courage and skill my daughter has demonstrated on dancing with the stars!” In a comment, Brinkley-Cook responded, "I love you."