Erdem's dress worn by Catherine, Duchess of Cambridge in Canada on June 30, 2011.

http://www.erdem.co.uk/collections/pre_spring_2012.php#pic20

http://www.dailymail.co.uk/news/article-2010012/Prince-William-Kate-Middleton-royal-visit-Canada.html
http://www.dailymail.co.uk/femail/article-2010024/Kates-transatlantic-transformation-Duchess-doubles-style-statements-mid-air-change.html