BLENHEIM, NEW ZEALAND - APRIL 10:  Prince William, Duke of Cambridge turns round and laughs to Catherine, Duchess of Cambridge and Sir Peter Jackson as he sits in a World War I Bi-plane during a visit to Omaka Aviation Heritage Centre on Day 4 of a Royal Tour to New Zealand on April 10, 2014 in Blenheim, New Zealand. The Duke and Duchess of Cambridge are on a three-week tour of Australia and New Zealand, the first official trip overseas with their son, Prince George of Cambridge.  (Photo by Chris Jackson/Getty Images)