Princess Diana's shocking death 24 years ago left not only her family but the whole country grief stricken.
Within hours of her death following a car crash in Paris, a sea of floral tributes started to build up outside the gates of Buckingham Palace as Britain tried to come to terms with what had happened.
Diana's sons Princes William and Harry and former in-laws, including the Queen, were on holiday in Balmoral on that terrible day in late August 1997.
It was agreed that the royals should stay at Balmoral in order to rally around Diana's mourning sons in private.
But anger started to grow among the public with the royals - especially with their reluctance to break one part of protocol.
At that time, it was established custom that a flag - the Royal Standard - would only be flown over Buckingham Palace if the monarch was present.
When Diana died, the Queen was at Balmoral so no flag was on display over the palace.
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In the days after her death, there was a growing feeling that a flag should be flown over the palace at half-mast as a mark of respect - despite this never happening before.
Tensions started boiling over, and resulted in the Queen's total break with protocol.
She agreed that the Union Flag could be flown at half-mast over Buckingham Palace on the day of Diana's funeral.
Since then, the Union flag does now fly at Buckingham Palace when the Queen is not in residence. When she is there it is replaced with the Royal Standard.
It has also been lowered to half mast to mark several occasions such as the death of the Queen Mother in 2002, the September 11 attacks in 2001 and the July 7 London bombings in 2005.
The Union Flag was also flown at half-mast over Buckingham Palace as a mark of respect on the first anniversary of the death of Diana on Bank Holiday, Monday, August 31, 1998.
