Emma Watson(Hermione) attends International Cartier Polo Event.

http://www.guardspoloclub.com/the-events/tournament/35

http://www.telegraph.co.uk/news/newstopics/theroyalfamily/2463329/Prince-Charles-oversees-Cartier-International-Polo-Day-in-absence-of-the-Queen,-William-and-Harry.html