Royals Prince William in a Tux, Prince Harry in a Suit: The Windsor Brothers Clean Up Well to Champion Their Causes The princes dusted off their finest for an evening that celebrated two causes close to their hearts By Erin Hill Erin Hill Twitter Senior News Editor, PEOPLE People Editorial Guidelines Published on September 17, 2015 06:10 PM Share Tweet Pin Email Photo: Chris Radburn/PA Wire/Zuma; Danny E. Martindale/Getty Everybody’s crazy ’bout a sharp-dressed man! Prince William and Prince Harry dusted off their finest for an evening that celebrated two causes close to their hearts. Harry, 31, was decked out in a cool blue suit for the Rugby World Cup welcome party on Thursday in London. The sports-loving prince, who is is the honorary president of England Rugby 2015, gave a warm speech on the eve of the six-week global tournament. “As a passionate rugby fan, I will share in the rollercoaster of emotions with millions of other fans around the world between now and Oct. 31,” he said. “It is this rollercoaster that makes sport – and especially rugby – so compelling. I have no doubt that all the highs and lows, the drama and tension, will create unforgettable memories.” Harry has long been a supporter of rugby and has backed several campaigns to motivate young people to take up the quintessentially English sport. “I believe that this World Cup – more than any before – has the potential to grow the game, both at home and abroad, by inspiring children of all backgrounds, and encouraging men and women of all ages and abilities, to embrace rugby,” he continued. The gracious host concluded his speech with a sweet invitation for the international players and fans. “I hope you all enjoy the tournament and while you’re here, make the most of what this country has to offer,” he said. Over on the other side of town, William, 33, broke out his tuxedo for the Tusk Trust 25th anniversary ball. The prince has been a royal patron of the conservation charity for almost a decade. The black-tie event, which was held at the Syon House and attended by 500 guests, celebrated the organization’s efforts to protect Africa’s wildlife. “Tusk has aged well, better even than me – and that’s to say nothing of the fast-greying founder and CEO Charlie Mayhew,” William joked at the start of his speech. “The need to protect wildlife in Africa is greater than ever before,” he continued. “We must take action…The illegal slaughter of elephants and rhino for their horns is barbaric, and it is not stylish to be associated with it. The problem, of course, is not unique to any part of the world – we must all do our best.” Conservation is one of the key causes both William and Harry have focused on, with Harry having just returned from a three-month conservation trip in Africa. “He is like an African man,” Simson Uri-Khob, CEO of Save The Rhino Trust and Harry’s expedition leader in Namibia, told PEOPLE. “He likes to be out there, sleeping under the stars knowing that he is close to danger.” Want to keep up with the latest royals coverage? Click here to subscribe to the Royals Newsletter.