Prince William’s fiancée is expected to leave her flowers on a black marble slab that covers the remains of the First World War soldier.
The Queen Mother began the long-standing tradition when her wedding posy was left at the grave in 1923 after her wedding to the Duke of York, later George VI.
The royal left the flowers in memory of her brother Fergus, killed in 1915 during the global conflict.
Tradition dictates that the day following royal weddings the floral tribute is sent to the Abbey after the official wedding pictures of the bride and groom have been taken.
The location of the Unknown Warrior’s resting place at the west end of the Abbey in the centre of the nave will also have a bearing on the bride’s procession to the altar.
Kate and her father Michael Middleton will have to make their way around the grave stone as it is the only one in the ancient building congregations are not allowed to walk on.
The Unknown Warrior’s body was brought from France and buried on Armistice Day, November 11 1920.
It is thought the idea came from the Rev David Railton, who had served as a chaplain on the Western Front.
To the surprise of the organisers during the week after the burial an estimated 1.2 million people visited the Abbey, and the site is now one of the most visited war graves in the world.
– The Telegraph – 04/23/11