Britain's Prince William

Britain's Prince William, the oldest son of Princess Diana and Prince Charles, turned 31 on June 21. The prince, also known as the Duke of Cambridge, is expecting his first child with wife, Catherine Middleton.

Britain's Prince William leaves after attending the wedding of the Duke and Duchess of Northumberland's daughter Lady Melissa Percy to chartered surveyor Thomas van Straubenzee at St Michael's Church in Alnwick, England, Saturday, June 22, 2013. (AP Photo/Scott Heppell)

Prince William

Prince William is seen making a royal salute as he watches the scene of Trooping the Colour from the balcony of Buckingham Palace with his brother Harry and mother Princess Diana in London in this June 15, 1985 file photograph. Britain's Prince William is to marry his long-term girlfriend Kate Middleton next year, Buckingham Palace said on November 16, 2010. REUTERS/Roy Letkey/Files

Prince William, right, holds a dog to his younger brother, Prince Harry on August 9, 1987, while on holiday with their parents the Prince and Princess of Wales, unseen. The Royal family is on holiday with King Juan Carlos of Spain, unseen, and his family at his Mediterranean Palace in Majorca. (AP Photo/John Redman)

Prince William

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Prince William

The Prince and Princess of Wales, Prince Harry, and housemaster Dr Andrew Gayley (behind) escort Prince William (2R), second in line to the throne, for his first day of term at the world famous Eton College September 6, 1995. REUTERS/Simon Kreitem

Prince William

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Prince William

Prince Charles stands with his sons Princes William (L) and Harry on the banks of the river Muick near Ballater August 16. The group are currently enjoying a summer break at Balmoral Castle. Reuters/ Jeff J Mitchell UK

Prince William

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Beaufort Polo Club - Charity Day

TETBURY, ENGLAND - JUNE 16: Prince William, Duke of Cambridge takes part in a charity polo day at Beaufort Polo Club on June 16, 2013 in Tetbury, England. (Photo by Mark Cuthbert/UK Press via Getty Images)

Trooping The Colour

LONDON, ENGLAND - JUNE 15: Prince William, Duke of Cambridge during the annual Trooping The Colour ceremony at Horse Guards Parade on June 15, 2013 in London, England. Today's ceremony which marks the Queens official birthday will not be attended by Prince Philip the Duke of Edinburgh as he recuperates from abdominal surgery and will also be The Duchess of Cambridge's last public engagement before her baby is due to be born next month. (Photo by Mark Cuthbert/UK Press via Getty Images)

Prince William marches with other Sandhurst Military Academy graduates in the Sovereign's parade Friday Dec. 15, 2006. Major General Sebastian Roberts, the general officer commanding the Household Division, who is ultimately William's new boss as he joins the Blues and Royals, said Friday that a deployment to a conflict zone for Prince William could not be ruled in or out.(AP Photo/Lewis Whyld, Pool)

Britains' Prince William interacts with members of the 3rd Battalion, Royal Australian Regiment during his unofficial visit to Sydney, Wednesday, Jan. 20, 2010. ( AP Photo/Rick Stevens, Pool)

FILE - In this April 29, 2011 file photo, Britain's Prince William and his wife Kate, Duchess of Cambridge stand outside of Westminster Abbey after their Royal Wedding in London. The couple celebrate their first anniversary on Sunday. (AP Photo/Martin Meissner, File)

(FILE) Prince William, Duke of Cambridge And Catherine, Duchess of Cambridge Celebrate Their First Wedding Anniversary

CALGARY, AB - JULY 08: (FILE PHOTO) A year ago tomorrow Prince William married Kate Middleton in a ceremony at Westminster Abbey watched by millions around the globe. The Duke and Duchess of Cambridge's first year has seen them attend a number of public engagements including a tour of Canada and North America last summer. Please refer to the following profile on Getty Images Archival for further imagery: http://www.gettyimages.co.uk/Search/Search.aspx?EventId=143604296&esource=maplinARC_uki_apr12 Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge wave as they attend the Calgary Stampede on July 8, 2011 in Calgary, Canada. The newly married Royal Couple are on the ninth day of their first joint overseas tour. The 12 day visit to North America is taking in some of the more remote areas of the country such as Prince Edward Island, Yellowknife and Calgary. The Royal couple started off their tour by joining millions of Canadians in taking part in Canada Day celebrations which mark Canada's 144th Birthday. (Photo by Chris Jackson/Getty Images)

Queen Elizabeth II and Members Of The Royal Family Attend The Order Of The Garter Service

WINDSOR, ENGLAND - JUNE 18: Prince William, Duke of Cambridge waves to the crowd as he attends the Order of the Garter procession and service at Windsor Castle on June 18, 2011 in Windsor, England. The Order of the Garter is the senior and oldest British Order of Chivalry, founded by Edward III in 1348. Membership in the order is limited to the sovereign, the Prince of Wales, and no more than twenty-four members. (Photo by Paul Edwards - WPA Pool/Getty Images)

Rhino Translocation Project

LYMPNE, ENGLAND - JUNE 06: Prince William, Duke of Cambridge smiles as he visits Port Lympne Wild Animal Park on June 6, 2012 in Port Lympne, England. Prince William, Duke of Cambridge was visiting the park to meet staff and rhinos involved in a translocation project. The Aspinall Foundation along with the Tusk Trust and the George Adamson Trust are combining forces to stage a rare translocation of three captive born black rhino to Mkomazi National Park in Tanzania in order to rejuvenate numbers of the black rhino in the area. The three animals are being airlifted in a dedicated DHL Boeing 757 from Manston Airport in Kent direct to Kilimanjaro Int Airport in Tanzania. The three black rhino have been donated by Damian Aspinall, Chairman of The Aspinall Foundation, from their breeding group at Port Lympne Wild Animal Park in Kent. The reintroduction of endangered species to the wild to assist breeding programmes is a major focus of The Aspinall Foundation. Prince William, Duke of Cambridge as Patron of Tusk Trust and a dedicated campaigner against poaching visited the rhinos at Port Lympne ahead of their translocation and today released a speech via the BBC highlighting his dedication to the fight against the illegal trade of ivory. (Photo by Chris Jackson/Getty Images)

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