Britain's Queen Elizabeth listens to Prime Minister David Cameron speak during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: POLITICS SOCIETY ROYALS TPX IMAGES OF THE DAY) 

Britain's Queen Elizabeth listens to Prime Minister David Cameron speak during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth listens during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth poses with members of the cabinet in the Pillarded Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth walks with Foreign Secretary William Hague, as she leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth walks with Foreign Secretary William Hague, as she leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth walks with Prime Minister David Cameron as members of the cabinet watch, at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth listens during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth takes her seat watched by members of the cabinet in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth listens during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth listens to Prime Minister David Cameron speak during a cabinet meeting in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth takes her seat watched by members of the cabinet in the Cabinet Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth poses with members of the cabinet in the Pillarded Room of Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Jeremy Selwyn/pool (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS TPX IMAGES OF THE DAY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth walks with Foreign Secretary William Hague, as she leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth walks with Foreign Secretary William Hague, as she leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth walks with Foreign Secretary William Hague, as she leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth leaves after attending a cabinet meeting at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: POLITICS SOCIETY ROYALS TPX IMAGES OF THE DAY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: POLITICS SOCIETY ROYALS) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee, the first monarch to do so since Queen Victoria. REUTERS/Toby Melville (BRITAIN - Tags: POLITICS SOCIETY ROYALS TPX IMAGES OF THE DAY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee. REUTERS/Toby Melville (BRITAIN - Tags: ROYALS POLITICS SOCIETY) 

Britain's Queen Elizabeth is greeted by Prime Minister David Cameron as she arrives at Number 10 Downing Street in London December 18, 2012. The Queen attended cabinet on Tuesday to mark her Diamond Jubilee. REUTERS/Stefan Wermuth (BRITAIN - Tags: POLITICS ROYALS ENTERTAINMENT SOCIETY) 

Britain's Prince William (L) and Catherine, Duchess of Cambridge are seen attending a reception at Guildhall to celebrate the Diamond Jubilee of Queen Elizabeth in London in this June 5, 2012 file photograph. Britain's Prince William and his wife Catherine are expecting a baby, the prince's office said on December 3, 2012. REUTERS/Chris Jackson/POOL/Files (BRITAIN - Tags: ROYALS ENTERTAINMENT) 

Canada's Parliamentary Budget Officer Kevin Page (R) receives the Queen Elizabeth II Diamond Jubilee medal from Senator Colin Kenny in Ottawa November 19, 2012. REUTERS/Blair Gable (CANADA - Tags: POLITICS) 

Britain's Prince Charles (R) speaks to the family of Lieutenant Timothy O'Donnell, who was killed in action in Afghanistan, during a farmers market walk about in Fielding November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) speaks to the family of Lieutenant Timothy O'Donnell, who was killed in action in Afghanistan, during a farmers market walk about in Fielding November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) shakes hands with a New Zealand Air Force staff member during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) speaks to a family member of Lieutenant Timothy O'Donnell, who was killed in action in Afghanistan, during a farmers market walk about in Fielding November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (2nd L) shakes hands with a New Zealand Air Force staff member during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (C) speaks to New Zealand Air Force staff during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) speaks to New Zealand Air Force staff during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (3rd L) walks to his plane after meeting with New Zealand Air Force staff and families during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (centre L) speaks to New Zealand Air Force staff during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (centre L) speaks to New Zealand Air Force staff during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) walks to his plane after meeting with New Zealand Air Force staff and families during a visit to Ohakea air base in Manawatu November 15, 2012. Prince Charles and his wife Camilla, the Duchess of Cornwall, visit New Zealand on the last leg of their tour of the Pacific to celebrate the diamond jubilee of Britain's Queen Elizabeth II. REUTERS/Marty Melville/Pool (NEW ZEALAND - Tags: ROYALS POLITICS MILITARY) 

Britain's Prince Charles (R) receives a traditional "hongi" greeting (or Maori greeting) during a walk along the Wellington waterfront November 14, 2012. Britain's Prince Charles and his wife, Camilla, Duchess of Cornwall, are on the last leg of a tour to mark Queen Elizabeth's diamond jubilee. REUTERS/Kent Blechynden/Pool (NEW ZEALAND - Tags: ENTERTAINMENT POLITICS ROYALS TPX IMAGES OF THE DAY) 

Britain's Prince Charles (L) receives a birthday gift as he greets well wishers during a walk along the Wellington waterfront November 14, 2012. Prince Charles celebrated his 64th birthday on Wednesday in Wellington, during the last leg of a tour to mark Queen Elizabeth's diamond jubilee. REUTERS/Kent Blechynden/Pool (NEW ZEALAND - Tags: ENTERTAINMENT POLITICS ROYALS) 

Britain's Camilla (L), Duchess of Cornwall, shakes hands with a woman in the crowd at the Auckland War Memorial Museum, after a ceremony to mark Armistice Day, November 11, 2012. Camilla, Duchess of Cornwall, and her husband Britain's Prince Charles are visiting New Zealand as part of celebrations to mark Queen Elizabeth's diamond jubilee. REUTERS/Greg Bowker/Pool (NEW ZEALAND - Tags: ROYALS POLITICS ANNIVERSARY ENTERTAINMENT) 

Britain's Prince Charles (front R) and his wife Camilla, Duchess of Cornwall, shake hands with well-wishers at the Auckland War Memorial Museum, after a ceremony to mark Armistice Day, November 11, 2012. The royal couple is visiting New Zealand as part of celebrations to mark Queen Elizabeth's diamond jubilee. REUTERS/Greg Bowker/Pool (NEW ZEALAND - Tags: ROYALS POLITICS ANNIVERSARY ENTERTAINMENT) 

Britain's Prince Charles shakes hands with a girl while interacting with well-wishers gathered at the Auckland War Memorial Museum, after a ceremony to mark Armistice Day, November 11, 2012. Prince Charles and his wife Camilla, Duchess of Cornwall, are visiting New Zealand as part of celebrations to mark Queen Elizabeth's diamond jubilee. REUTERS/Greg Bowker/Pool (NEW ZEALAND - Tags: ROYALS POLITICS ANNIVERSARY ENTERTAINMENT) 

Britain's Prince Charles chats with returned soldier Frank Sharman (L) as his wife Camilla, Duchess of Cornwall talks with returned soldier Colin Stanbridge (2nd L) as they attend the Armistice Day Commemoration at the Auckland War Memorial Museum, November 11, 2012. Prince Charles and his wife Camilla are in Auckland, New Zealand, for the final leg of their Pacific tour to commemorate the diamond jubilee of his mother Queen Elizabeth. REUTERS/Nigel Marple (NEW ZEALAND - Tags: ROYALS ANNIVERSARY MILITARY) 

Britain's Prince Charles chats with returned soldier Colin Stanbridge as he attends the Armistice Day Commemoration at the Auckland War Memorial Museum, November 11, 2012. Prince Charles and his wife Camilla, Duchess of Cornwall, are in Auckland, New Zealand, for the final leg of their Pacific tour to commemorate the diamond jubilee of his mother Queen Elizabeth. REUTERS/Nigel Marple (NEW ZEALAND - Tags: ROYALS ANNIVERSARY MILITARY) 

Britain's Prince Charles (2nd L) and his wife Camilla, Duchess of Cornwall, attend an event to commemorate Armistice Day at the Auckland War Memorial Museum November 11, 2012. The royal couple are visiting New Zealand as part of celebrations to mark Queen Elizabeth's diamond jubilee. REUTERS/Greg Bowker/Pool (NEW ZEALAND - Tags: ROYALS MILITARY POLITICS ANNIVERSARY) 

Britain's Prince Charles holds a wreath during an event to commemorate Armistice Day at the Auckland War Memorial Museum November 11, 2012. Prince Charles and his wife Camilla, Duchess of Cornwall, are visiting New Zealand as part of celebrations to mark Queen Elizabeth's diamond jubilee. REUTERS/Greg Bowker/Pool (NEW ZEALAND - Tags: ROYALS MILITARY POLITICS ANNIVERSARY)