In a battle between two wildcard teams, the all-British pairing of Barnett and O'Mara edged former Doubles World No.1 players Williams and Murray, 3-6, 6-4, 7-6[18-16] in a two-hour and 12-minute clash on No.2 Court.
She retired as one of the most accomplished players ever - two Olympic and five World Championships gold among the several titles she picked up in her career.
Zhang's retirement in the singles meant that Shuai Zhang and partner, Elise Mertens, were unable to compete in the doubles final, meaning that Jelena Ostapenko and Lyudmyla Kichenok received a walkover to win the title.