CANBERRA, AUSTRALIA- APRIL 24:  (NO UK SALES FOR 28 DAYS)  Catherine, Duchess of Cambridge helps children water a tree as she visits the National Arboretum on April 24, 2014 in Canberra, Australia. 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 Pool/Samir Hussein/WireImage)