The Queen has turned 95 today and she is marking the milestone privately following the death of her "beloved" husband the Duke of Edinburgh.
Members of the monarchy have been supporting the Queen throughout the mourning period for Prince Philip, and some of her family are expected to be with her at Windsor Castle.
Her birthday on Wednesday was within the two-week period of royal mourning, which is being observed until Friday.
The Royal Family released a statement on social media saying: "Today is The Queen’s 95th birthday.
"The Queen was born at 2.40am on 21 April 1926 at 17 Bruton Street in Mayfair, London. She was the first child of The Duke and Duchess of York, who later became King George VI and Queen Elizabeth.
"This year Her Majesty remains at Windsor Castle, during a period of Royal Mourning following the death of The Duke of Edinburgh."
The message was accompanied by an image of the Queen smiling. The picture was taken on a previous occasion and no official image taken on her birthday is expected to be released.
Boris Johnson said he was "proud" to serve as the Queen's Prime Minister.
He wrote on Twitter: "I would like to send my warm wishes to Her Majesty The Queen on her 95th birthday.
"I have always had the highest admiration for Her Majesty and her service to this country and the Commonwealth. I am proud to serve as her Prime Minister."
Philip's family and friends gathered at St George's Chapel in Windsor on Saturday to say their final farewell to the duke, who died peacefully on April 9.
His death came a few months before his 100th birthday, which was due to be the focus of royal celebrations this year, while the Queen's 95th was to be more low-key.
After 73 years of married life the Queen now reigns alone without the support of her "strength and stay", as she famously described her late husband.
According to reports, some family members, including Princess Anne, were planning to visit The Queen on Wednesday.
And The Mirror reported that Prince Andrew, granddaughter Eugenie and her newborn son August had arranged a birthday walk with the Queen.
Royal expert Russell Myers agrees and told TV presenter Lorraine Kelly said: “Andrew will be visiting, he lives close by.
"Princess Eugenie and her little baby August will also be popping along. They are staying on the Windsor estate as well."
