The recent abdication of Pope Benedict and the Netherlands' Queen Beatrix have fuelled speculation in Britain Queen Elizabeth may also end her 61-year reign.
The monarch, 87, has been avoiding long flights and her son, Prince Charles, and grandson, Prince William, have toured on her behalf.
For the first time the Queen will not be at the Commonwealth heads of government summit in Sri Lanka this year.
There has been speculation that the Queen might call it a day.