The Queen turns 95 today as she marks her first birthday without Prince Philip in seven decades.
The world's oldest reigning head of state is expected to stay at Windsor Castle today.
There will be no public celebration unlike on her official birthday, which is marked on the second Saturday in June.
The tradition of monarchs having two birthdays dates back to 1748, when King George II moved his big day to the summer so he could enjoy a huge parade.
As the Queen is currently in mourning there will be no celebrations to mark her real birthday today.
The gun salutes that normally take place at the Tower of London and Hyde Park have been cancelled in honour of Prince Philip, who died aged 99 on April 9.
Members of the royal family have agreed to carry out a rota to visit the Queen in the coming days to make sure she is not left alone as she grieves.
Princess Anne and Sophie, the Countess of Wessex, are among the Queen's first guests.
The head of state is also set to see her son Andrew, granddaughter Eugenie and her newborn son August today as they make their way over from their homes on the Windsor estate.
A royal source: “The Queen is hoping to take advantage of the good weather as much as possible to join family members to walk her two new corgi puppies Fergus and Muick.
“She is very much looking forward to seeing her family who have been a great comfort to her and one another as they continue to mourn the loss of Prince Philip.”
Buckingham Palace said there were no plans to release an official picture to mark the occasion, as had happened in previous years.
An official royal mourning period of two weeks is due to end on Thursday when the royals are expected to return to planned engagements.
The Prince of Wales has retreated alone to his official Welsh home to mourn the loss of the Duke of Edinburgh.
Charles is staying at Llwynywermod, his Welsh property in Llandovery, Myddfai, after the family said goodbye to the Duke of Edinburgh at St George’s Chapel on Saturday.
