A child brings flowers to a makeshift altar outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

A mourner draped in a British Union Jack flag takes pictures of the flowers placed outside Windsor Castle after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

Maggie, 2, lays down a bouquet of flowers outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A person holds a flag while looking to Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A picture of Britain's Prince Philip, husband of Queen Elizabeth, is seen in the newspapers wrapped around flowers, after he died at the age of 99, in London, Britain, April 9, 2021.

Bouquets of flowers and a flag are laid down outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Evie Bedford, 7, lays down a bouquet of flowers outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Windsor Castle wardens move flowers which were placed by members of the public after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

Horse Racing - Grand National Festival - Aintree Racecourse, Liverpool, Britain - April 9, 2021 The Union Jack flag flies at half mast after Buckingham Palace announced Britain's Prince Philip, husband of Queen Elizabeth had died at the age of 99.

A British Union Jack flag flies at half-mast on top of the Victoria Tower, part of the Houses of Parliament, after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners lay down flowers outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A picture of Britain's Prince Philip, husband of Queen Elizabeth, is seen in a newspaper as people gather near the Queen Victoria Memorial, after he died at the age of 99, in London, Britain, April 9, 2021.

Children lay down flowers outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A mourner prays outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

Children bring a bouquet of flowers to Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Bouquets of flowers and messages of condolence are laid down outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Bouquets of flowers are laid down outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A mourner cries outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A mourner cries outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Horse Racing - Grand National Festival - Aintree Racecourse, Liverpool, Britain - April 9, 2021 Jockeys, owners and trainers stand during a minutes silence after Buckingham Palace announced Britain's Prince Philip, husband of Queen Elizabeth had died at the age of 99.

A card attached to the flowers is seen outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

Bouquets of flowers are laid down outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners gather outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A mourner brings flowers to Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners hug as they gather outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A mourner brings flowers to Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A man looks on as he holds a flag outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A mourner prays outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A mourner with a dog brings flowers to Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A British Union Jack flag flies at half-mast on top of the Edinburgh castle, as a Scottish flag flies at half-mast next to it, after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Edinburgh, Scotland, Britain, April 9, 2021.

Windsor Castle wardens move flowers which were placed by members of the public outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A man gestures in front of Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

A sign announcing the death of the Britain's Prince Philip, Duke of Edinburgh, who has died at the age of 99, is placed on the gates of Buckingham Palace, in London, Britain April 9, 2021. Ian West/Pool via REUTERS

A mourner stands outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners gather outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners gather outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

Mourners embrace as they gather outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

A bouquet of flowers with a note is seen outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

A British flag is seen at half mast at the British embassy in Unites States after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Washington, U.S. April 9, 2021.

People gather outside Windsor Castle after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A mourner lays down flowers outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A girl smells the flowers outside Windsor Castle after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

A man gestures in front of Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

Bouquets of flowers are laid down outside Buckingham Palace after it was announced that Britain's Prince Philip, husband of Queen Elizabeth, has died at the age of 99, in London, Britain, April 9, 2021.

A child leaves flowers outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

People gather outside Buckingham Palace after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in London, Britain, April 9, 2021.

A candle is seen among flowers outside Windsor Castle after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Windsor, near London, Britain, April 9, 2021.

People light a candle outside Windsor Castle after Britain's Prince Philip, husband of Queen Elizabeth, died at the age of 99, in Windsor, near London, Britain, April 9, 2021.