Charles is Queen's Abbey stand-in
The Prince of Wales has stood in for the Queen in recreating a historic Order of the Bath service image - echoing a painting of George V.
The Queen attended the Westminster Abbey service and played her part in the ceremonial events but, in a change of plan, was not photographed making an offering of gold and silver coins.
The image would have been similar to a painting depicting her father carrying out the same symbolic gesture more than 80 years ago, but capturing the image would have meant the Queen making an extra journey up and down some steep steps in full regalia.
A Palace spokesman said that, in order to "ease the Queen's comfort", the heir to the throne stepped in to make the offering of the precious metals in the Abbey's Lady Chapel of King Henry VII.
The spokesman said: "The decision was taken to lessen the burden of the Queen during the ceremonial service - it's for the Queen's comfort coming into and out of the stalls."
The spokesman stressed that the sovereign's stall, or seat, within the Tudor chapel was reached by very steep wooden steps and she had been wearing her full regalia.
There was no suggestion the Queen was unwell, and she and her Royal Household took the decision to change the plans following a dress rehearsal yesterday.
The Order of the Bath service, held every four years, is always attended by Charles but he is joined every eighth year by the Queen, who was last present in May 2006.
It is usually awarded to high ranking officers of the armed services and to a small number of senior civil servants.
The order originated in the medieval period when the honour was only conferred on a knight after he had performed a number of rituals designed to purify the inner soul - fasting, vigils and prayer, and cleansing by bathing.
George I revived it in 1725 as a regular military order, to serve the purposes of the then prime minister Sir Robert Walpole, who required an additional source for political reward.
The Queen is Sovereign Head of the military order while Charles is its Great Master.
During the service a number of senior military figures were installed as Knights Grand Cross replacing previous holders who had died.
They included retired naval officer Admiral Sir Jock Slater, former chief of naval staff and first sea lord, and Field Marshal, Lord Guthrie of Craigiebank, former head of the British Army.
The service was a spectacle of pomp and ceremony with the Queen, Prince and the Knights processing through the Abbey wearing their flowing cerise-coloured mantels.
The monarch was dressed in the mantel of sovereign of the Order and her long train was carried above the floor by her page Hugo Bertie, 12, who is related to the Queen Mother's family.
She also wore a white gown by Angela Kelly and the Queen Mary tiara.
The former high-ranking military officers and the senior royals walked past the congregation to the chapel at the eastern end of the Abbey.
Members of the public were not seated in the chapel, so flat screen televisions relayed the events inside and Charles could be seen walking down around six steep steps from his stall, to make the offering.
A photograph was taken to capture the moment and it bears similarities with the painting by Francis Owen Salisbury who depicted Charles' great grandfather George V in the same setting.
The canvas was presented to the King in July 1929 and shows him at the foot of the altar in full regalia.
Charles was flanked by the new knights who stood in a line either side of him and, in a symbolic surrendering of worldly treasures, placed two bags containing the coins on a plate held by the Abbey's Dean, the Very Reverend Dr John Hall.
The Queen could not be seen on the flat-screen televisions but from her seat, above the stalls of the Knights, would have had a good view of the ceremony to install the new members of the Order.
Charles stood in for the Queen when it was decided she would not travel to Sri Lanka for a Commonwealth leaders summit in 2013, following a review of her long-haul flights by Buckingham Palace.
The ceremony to install the new Knights Grand Cross involved them offering up their swords - to remind them to use their weapons first for the glory of God and second in the defence of the gospel - and the swearing of an oath to love the Queen and "defend maidens, widows and orphans".
All the members of the Order left the chapel, and before the service was over the National Anthem was sung.
Senior figures who are already Knights include former heads of the Army General Sir Mike Jackson and General Lord Dannatt, and Lord Janvrin, a former private secretary to the Queen.
As the ceremony drew to a close, one of the Her Majesty's Body Guard of the Honourable Corps of Gentlemen at Arms, who were on duty, collapsed and was taken away by an ambulance crew.