LONDON, APRIL 21

Queen Elizabeth II is marking her 95th birthday in a low-key fashion at Windsor Castle, just days after the funeral of her husband, Prince Philip.

Some members of the royal family are expected to be with the queen on Wednesday. Her birthday falls within the two-week royal mourning period for Philip that is being observed until Friday.

British Prime Minister Boris Johnson was one of many people who sent best wishes to the monarch.

'I have always had the highest admiration for Her Majesty and her service to this country and the Commonwealth,' Johnson said on Twitter. 'I am proud to serve as her prime minister.'

Philip, also known as the Duke of Edinburgh, died on April 9 at age 99. Family and friends gathered for his funeral at St George's Chapel in Windsor on Saturday to say their final farewells.

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 always set to be a more low-key event.