LONDON, ENGLAND - SEPTEMBER 14: Jemma Wellesley, Countess of Mornington, and Arthur Wellesley, Earl of Mornington, attend The London 2014 Stella McCartney Green Carpet Collection during London Fashion Week at The Royal British Institute on September 14, 2014 in London, England. (Photo by David M. Benett/Getty Images for Eco-Age/Green Carpet Collection)

LONDON, ENGLAND - SEPTEMBER 14:  Jemma Wellesley, Countess of Mornington, and Arthur Wellesley, Earl of Mornington, attend The London 2014 Stella McCartney Green Carpet Collection during London Fashion Week at The Royal British Institute on September 14, 2014 in London, England.  (Photo by David M. Benett/Getty Images for Eco-Age/Green Carpet Collection)