The Prince and Princess of Wales were at the forefront of the pomp and pageantry this morning as the King and Queen welcomed the Sultan of Oman on a State Visit to the United Kingdom.
William and Catherine are in Windsor to greet the Omani ruler with Their Majesties at the start of a three-day official visit at the request of the British government focusing on trade, diplomacy, military and cultural ties.
The trio were met with a royal salute from the waiting Sovereign's Escort and the national anthem, played by a military band.
Amid drizzly autumnal weather, the royal party made their way up the steps to stand under the covered dais, with the monarch holding his closed umbrella.
The King was dressed in top hat and tails, while Camilla wore a red wool crepe dress and coat by Fiona Clare, hat by Philip Treacy and ruby and diamond flower brooch – with the colour seemingly a nod to the Omani flag, as was Kate's dark green coat dress.
His Majesty Sultan Haitham bin Tarik was earlier greeted by Prince William on behalf of the monarch at one of his private UK residences, before travelling to Windsor together.
In a change to the traditional arrangements, the Princess of Wales did not accompany William to greet the Sultan, but instead waited alongside the King and Queen.
The planned adjustment was made because the Sultan is not being accompanied by his wife during his stay.
Kate's dark green coat dress appeared to be a nod to the Omani flag
The King was dressed in top hat and tails, while Camilla wore a red wool crepe dress and coat by Fiona Clare, hat by Philip Treacy and ruby and diamond flower brooch
His Majesty Sultan Haitham bin Tarik was earlier on Tuesday greeted by Prince William on behalf of the monarch at one of his private UK residences
Meanwhile the King and Queen, accompanied by Catherine, arrived separately from Windsor Castle to formally welcome The Sultan at the Royal Dais on Datchet Road.
A Royal Salute is due to be fired at the Home Park in Windsor, and at the Tower of London.
The Sultan will later join The King and Queen, and The Prince and Princess of Wales, in a carriage procession through Windsor town to Windsor Castle.
The King and the Sultan are expected to travel in the Irish State Coach, with the Queen and H.H. Sayyid Shihab bin Tariq Al Said, Deputy Prime Minister for Defence Affairs, behind in the Scottish State Coach.
The Prince and Princess of Wales will be together in the Australian State Coach along with H.H. Sayyid Theyazin bin Haitham Al Said, Deputy Prime Minister for Economic Affairs, and H.H. Sayyid Loay bin Ghalib Al Said, Secretary General of the Diwan of the Royal Court.
Two Ascot Landaus will bring up the rear of the procession containing assorted members of the Omani Royal Court and government.
Taking in Thames Street High Street, Park Street and the castle's Cambridge Gate - with the route lined by an impressive display of all three Armed Forces - the procession entered through the George IV Gateway into the Quadrangle of Windsor Castle.
The Military Knights of Windsor will be in position at the Sovereign's Entrance with a detachment of the Household Cavalry, along with The King's Body Guard of the Yeomen of the Guard.
The Sultan will later join The King and Queen, and The Prince and Princess of Wales, in a carriage procession through Windsor town to Windsor Castle
The state visit is a first by an Omani ruler for 44 years, the last one being hosted by Queen Elizabeth II at Buckingham Palace in 1982
A Guard of Honour, formed by the Nijmegen Company Grenadier Guards and F Company Scots Guards, with the Royal Standards of the Regiment and the Band of the Scots Guards, will be mounted in the Quadrangle of Windsor Castle.
The Guard of Honour will give a Royal Salute and the regimental Band will play the Omani and British National Anthems as the carriage procession arrives.
The Sultan, accompanied by The King, will inspect the Guard of Honour, before rejoining The Queen, and The Prince and Princess of Wales, to view the impressive military rank and March past.
Following a private lunch in the State Dining Room, joined by Members of The Royal Family, Their Majesties will invite The Sultan to view a special exhibition of items relating to Oman from the Royal Collection, in the Green Drawing Room.
In the evening, His Majesty, accompanied by The Queen and Members of the Royal Family, will give a glittering State Banquet at Windsor Castle for The Sultan - the highlight of which will undoubtedly be the ladies' gowns and tiaras.
The King and His Majesty Sultan Haitham bin Tarik will deliver speeches at the beginning of the banquet.
The present Sultan acceded to the throne in 2020 following the death of his cousin, Sultan Qaboos bin Said, becoming the fifteenth ruler of the Al Bu Said dynasty which has ruled Oman since the mid-eighteenth century.
He has also been dubbed 'one of the most discreet billionaires alive'.
The sultan is married with four children, although his wife is not accompanying him on this State Visit.
The ruling Omani family has enjoyed good relations with the British royal family and the Sultan has met the King and Queen on several occasions previously. Oman is considered one of Britain's oldest friends in Arabia.
One of the Sultan's main challenges is seen to be the need to oversee Oman's transition from over-reliance on oil revenues to a diversified economy.