Service Of The Order Of The Garter at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England. The Order of the Garter is the most senior and the oldest British Order of Chivalry and was founded by Edward III in 1348.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Princess Anne, Princess Royal and Prince Richard, Duke of Gloucester attend the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

(L-R)  Prince Andrew, Duke of York, Prince Edward, Earl of Wessex, Prince William, Duke of Cambridge (barely see him behind Prince Edward) and Prince Charles, Prince of Wales attend the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

(L-R) Prince Andrew, Duke of York and Prince Edward, Earl of Wessex attend the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince Charles, Prince of Wales attends the Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

 Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

 Princess Anne, Princess Royal attends the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II leaves the Order of the Garter Service at St George's Chapel in a royal carriage at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II leaves the Order of the Garter Service at St George's Chapel in a royal carriage at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge leaves the Order of the Garter Service at St George's Chapel in a royal carriage at Windsor Castle on June 15, 2015 in Windsor, England.

Elizabeth II leaves the Order of the Garter Service at St George's Chapel in a royal carriage at Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II leaves the Order of the Garter Service at St George's Chapel in a royal carriage at Windsor Castle on June 15, 2015 in Windsor, England.

Prince Andrew, Duke of York and Prince Charles, Prince of Wales attend the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II attends the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge and Prince Charles, Prince of Wales attend the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

  Prince Andrew, Duke of York and Prince Edward, Earl of Wessex attend the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Queen Elizabeth II and Prince Philip, Duke of Edinburgh attend the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

(R) Birgitte, Duchess of Gloucester and Princess Anne, Princess Royal attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince Charles, Prince of Wales and Prince William, Duke of Cambridge attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Birgitte, Duchess of Gloucester and Prince Edward, Duke of Kent takes part in the Trooping the Colour Ceremony on June 13, 2015 in London, England.

Birgitte, Duchess of Gloucester and Prince Edward, Duke of Kent takes part in the Trooping the Colour Ceremony on June 13, 2015 in London, England.

(L-R) Camilla, Duchess of Cornwall, Sophie, Countess of Wessex and Birgitte, Duchess of Gloucester attend the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Prince Edward, Duke of Kent and Princess Alexandra attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince Charles, Prince of Wales and Prince Edward, Earl of Wessex attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

 Prince Edward, Earl of Wessex and Sophie, Countess of Wessex attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge attends The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

  Queen Elizabeth II and Prince Philip, Duke of Edinburgh attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge attends The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

  Prince Edward, Earl of Wessex attends The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Sophie, Countess of Wessex attend The Order of the Garter Service at St George's Chapel at Windsor Castle on June 15, 2015 in Windsor, England.

Prince Charles, Prince of Wales, Camilla, Duchess of Cornwall and Prince William, Duke of Cambridge leave after the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Sophie, Countess of Wessex and Prince Edward, Earl of Wessex leave after the Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.

Prince William, Duke of Cambridge parades during the annual Order of the Garter Service at St George's Chapel in Windsor Castle on June 15, 2015 in Windsor, England.