Kate, the Duchess of Cambridge congratulates her husband Prince William, Duke of Cambridge at the trophy ceremony after his team won the charity polo match at The Santa Barbara Polo & Racquet club on Saturday, July 9, 2011 in Carpinteria, Calif. The event was held in support of The American Friends of The Foundation of Prince William and Prince Harry. | AP

Britain's Prince William and his fiance Kate Middleton react following a naming ceremony and Service dedication for the Royal National Lifeboat Institution's new Atlantic 85 Lifeboat, at Trearddur Bay Lifeboat Station in Anglesey, Wales, Thursday Feb. 24, 2011. | AP

Britain's Prince William and his fiance Kate Middleton react following a naming ceremony and Service dedication for the Royal National Lifeboat Institution's new Atlantic 85 Lifeboat, at Trearddur Bay Lifeboat Station in Anglesey, Wales, Thursday Feb. 24, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, are greeted by Canadian Foreign Affairs Minister John Baird upon their arrival in Ottawa, Canada, on their first official overseas trip Thursday, June 30, 2011. | AP

Prince William, The Duke of Cambridge, is given a stuffed toy animal from someone in the crowd as he tour Slave Lake, Alberta, Canada on Wednesday, July 6, 2011. | AP

In this image taken from video, Britain's Prince William, left, places the ring on the finger of his bride, Kate Middleton, as they stand at the altar at Westminster Abbey for the Royal Wedding in London on Friday, April 29, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, arrive at Los Angeles International Airport in Los Angeles on Friday, July 8, 2011. | AP

Kate Middleton tosses a pancake as Prince William looks on during a visit to City Hall on March 8, 2011 in Belfast, Northern Ireland. | Getty

Prince William and Kate, the Duke and Duchess of Cambridge, left, arrive with former Ambassador to Jamaica, Glen Holden, right, and Gloria Holden at a charity polo match at the Santa Barbara Polo & Racquet Club in Carpinteria, Calif., Saturday, July 9, 2011. The event is held in support of The American Friends of The Foundation of Prince William and Prince Harry. | AP

Britain's Prince William kisses his wife Kate, Duchess of Cambridge, on the balcony of Buckingham Palace after the Royal Wedding in London Friday, April, 29, 2011. | AP

Kate Middleton and Prince William visit Greenmount Agricultural College on March 8, 2011 in Belfast, Northern Ireland. | Getty

Prince William and Kate, the Duke and Duchess of Cambridge walk down the stairs of their aircraft upon their arrival in Ottawa, Canada, on their first official overseas trip Thursday, June 30, 2011. | AP

The Duchess of Cambridge, Kate, greets people in Slave Lake, Alberta, Canada on Wednesday, July 6, 2011. | AP

Prince William and wife Kate, the Duke and Duchess of Cambridge, share a laugh at a ceremony at Province House in Charlottetown on Prince Edward Island as part of their Royal Tour of Canada, Monday, July 4, 2011. | AP

Prince William and his wife, Catherine, Duchess of Cambridge, watch a dance presentation Sunday in Los Angeles. | Liz O. Baylen~AP

Prince William and Kate, the Duke and Duchess of Cambridge, greet youths as they tour la Maison Dauphine in Quebec City, Sunday, July 3, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, arrive at a charity polo match at the Santa Barbara Polo & Racquet Club in Carpinteria, Calif., Saturday, July 9, 2011. The event is held in support of The American Friends of The Foundation of Prince William and Prince Harry. | AP

In this July 4, 2011 file photo, Prince William and Kate, the Duke and Duchess of Cambridge wave to the crowd as they board the plane in Summerside, Prince Edward Island. The couple will arrive Friday, July 8, in California, a state that in the years since Princess Diana’s death has passed three laws intended to curb paparazzi abuses. | AP

Prince William, and his wife, Kate, the Duke and Duchess of Cambridge, greet their admirers in Yellowknife, Northwest Territories on Tuesday, July 5, 2011. | AP

Kate, the Duchess of Cambridge congratulates her husband Prince William, Duke of Cambridge at the trophy ceremony after his team won the charity polo match at The Santa Barbara Polo & Racquet club on Saturday, July 9, 2011 in Carpinteria Calif. The event was held in support of The American Friends of The Foundation of Prince William and Prince Harry. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, share a laugh onstage at the Service Nation: Mission Serve Hiring Our Heroes Los Angeles job fair event at Sony Pictures Studios in Culver City, Calif., Sunday, July 10, 2011. | AP

Prince William, and his wife Kate, the Duke and Duchess of Cambridge, look at a stuffed bear destined for children of military families at Sony Studios in Culver City, Calif., Sunday, July 10, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, arrive at the Service Nation: Mission Serve Hiring Our Heroes Los Angeles job fair event at Sony Pictures Studios in Culver City, Calif., Sunday, July 10, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, take part in a morning prayer service on board HMCS Montreal in Quebec City, Sunday, July 3, 2011. | AP

Prince William speaks at a charity polo match at the Santa Barbara Polo & Racquet Club in Carpinteria, Calif., on Saturday, July 9, 2011. The event is held in support of The American Friends of The Foundation of Prince William and Prince Harry. | AP

Prince William and his wife, Kate, the Duke and Duchess of Cambridge greet well-wishers as they tour Slave Lake, Alberta, Canada on Wednesday, July 6, 2011. | AP

Prince William and wife Kate, the Duke and Duchess of Cambridge participate in Canada Day celebrations on Parliament Hill Friday, July 1, 2011 in Ottawa, Ontario. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, look on during remarks by Nigel Sheinwald, British ambassador to the United States, during a private reception at the British Consul-General's residence in Los Angeles, Friday, July 8, 2011. | AP

William and Kate, the Duke and Duchess of Cambridge share a laugh during a citizenship ceremony at the Museum of Civilization in Gatineau, Canada, on Friday, July 1, 2011. | AP

The Duke and Duchess of Cambridge walk hand in hand from Buckingham Palace in London Saturday April 30 2011, the day after their wedding. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, arrive at the inaugural BAFTA Brits to Watch 2011 event at the Belasco Theater in Los Angeles, Saturday, July 9, 2011. At left is BAFTA chairman Amanda Berry. | AP

The Duke and Duchess of Cambridge walk hand in hand from Buckingham Palace in London Saturday April 30 2011, the day after their wedding. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, look on during a private reception at the British Consul-General's residence in Los Angeles, Friday, July 8, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, wave as they board their plane as they leave Ottawa, Ontario , en route to Montreal as they continue their Royal Tour of Canada Saturday, July 2, 2011. | AP

She's No. 1: Prince William and wife Kate, the Duke and Duchess of Cambridge, receive Team Canada hockey jerseys after they took part in street hockey Tuesday in Yellowknife, Northwest Territories. | AP

Prince William and Kate, the Duke and Duchess of Cambridge talk during a Canada Day celebration on Parliament Hill in Ottawa, Canada, as part of their Royal Tour of Canada Friday, July 1, 2011. | AP

Prince William and Kate, the Duke and Duchess of Cambridge, arrive at a tree planting ceremony at Rideau Hall in Ottawa, Ontario, as part of their Royal Tour of Canada Saturday, July 2, 2011. | AP

Happy Birthday, Kate! Kate Middleton turns 30 years-old today. Palace officials said the Duchess of Cambridge’s birthday celebration will be a “low-key and private” affair. Prince William and Kate attended the "War Horse" movie premiere in London on Sunday.

William and Kate, the Duke and Duchess of Cambridge take part in Canada Day celebrations on Parliament Hill in Ottawa on Friday, July 1, 2011. | AP

Prince William and his wife Kate, the Duke and Duchess of Cambridge, arrive in Charlottetown on Prince Edward Island as part of their Royal Tour of Canada, Sunday, July 3, 2011. | AP