Irish President Michael D Higgins inspected the tribute to brave Irish soldiers which has been given pride of place in Windsor Castle.
On the second day of his historic state visit, he and his wife Sabina viewed the colours of the regiments of the British army that were disbanded when Ireland gained independence.
They were given pride of place in a stairway entrance to Windsor Palace, so that everyone could see them, on the insistence of King George V in 1922.
The colours, which honour the service of Irish soldiers in the First World War and other times of battle, have never been moved from their permanent setting - except when the 1992 Windsor fire threatened to destroy them.
"Needs must, we took them out," the Duke of York, who is the colonel-in-chief, the Royal Irish Regiment, told the couple .
They have been held at Windsor since the establishment of the Irish Free State in 1922, when the six regiments of the British army from that part of Ireland which had become the Free State were disbanded.
In a message to all six regiments at the time, King George V said: "The Colours are to be preserved and held in reverence at Windsor Castle as a perpetual record of your noble exploits in the field."
The presidential couple looked over the colours of the Royal Irish Regiment, the Royal Dublin Fusiliers, the Connaught Rangers, the Prince of Wales' Leinster Regiment (Royal Canadians), and the Royal Munster Fusiliers. The South Irish Horse did not have a colour.
There were 58,000 Irish soldiers in the British army at the start of the First World War, 140,000 volunteered for units that were stationed in Ireland during the war and tens of thousands of Irish people died during that conflict .
This is the first state visit to the United Kingdom by an Irish president and its significance has been her deepened by the invitation for the first couple to stay at the Queen's home, Windsor Castle.
The Queen and the Duke of Edinburgh paid a state visit to Ireland in May 2011.