Court ceremonies
taken from wikipedia

The State Ballroom is the largest room at Buckingham Palace. It was added by Queen Victoria and is used for ceremonies such as investitures and state banquets. This picture dates from 1856. The polychrome colour scheme has been replaced by mainly white decoration with gold details and red upholstery.
During the current reign court ceremony has undergone a radical change, and entry to the palace is no longer the prerogative of just the upper class.[18]
There has been a progressive relaxation of the dress code governing formal court uniform and dress. In previous reigns, men not wearing military uniform wore knee breeches of an 18th-century design. Women's evening dress included obligatory trains and tiaras and/or feathers in their hair. After World War I, when Queen Mary wished to follow fashion by raising her skirts a few inches from the ground, she requested a Lady-in-Waiting to shorten her own skirt first to gauge the King's reaction. King George V was horrified and Queen Mary's hemline remained unfashionably low. Subsequently, King George VI and Queen Elizabeth allowed daytime skirts to rise.
Today there is no official dress code.[19] Most men invited to Buckingham Palace in the daytime choose to wear service uniform or morning coats, and in the evening, depending on the formality of the occasion, black tie or white tie. If the occasion is 'white tie' then women, if they possess one, wear a tiara.
One of the first major changes was in 1958 when the Queen abolished the presentation parties for debutantes.[20] These court presentations of aristocratic girls to the monarch took place in the Throne room. Debutantes wore full court dress, with three tall ostrich feathers in their hair. They entered, curtsied, performed a choreographed backwards walk and a further curtsey, while manoeuvring a dress train of prescribed length. The ceremony corresponded to the "court drawing rooms" of earlier reigns, and Queen Elizabeth II replaced the presentations with large and frequent palace garden parties for an invited cross-section of British society. The late Princess Margaret is reputed to have remarked of the debutante presentations: "We had to put a stop to it, every tart in London was getting in".[21] Today, the Throne Room is used for the reception of formal addresses such as those given to the Queen on her Jubilees. It is here on the throne dais that royal wedding portraits and family photographs are taken.
Investitures, which include the conferring of knighthoods by dubbing with a sword, and other awards take place in the palace's Victorian Ballroom, built in 1854. At 123 ft by 60 ft (37 m by 20 m), this is the largest room in the palace. It has replaced the Throne room in importance and use. During investitures the Queen stands on the throne dais beneath a giant, domed velvet canopy, known as a shamiana or a baldachin, used at the coronation Durbar in Delhi in 1911. A military band plays in the musicians' gallery, as the recipients of awards approach the Queen and receive their honours, watched by their families and friends.

This 1870 drawing shows guests ascending the Grand Staircase.
State banquets also take place in the Ballroom. These formal dinners take place on the first evening of a state visit by a visiting Head of State. On these occasions, often over 150 guests in formal "white tie and decorations" including tiaras for women, dine off gold plate. The largest and most formal reception at Buckingham Palace takes place every November, when the Queen entertains members of the foreign diplomatic corps resident in London. On this occasion all the state rooms are in use, as the Royal Family proceed through them [22] beginning their procession through the great north doors of the Picture Gallery. As Nash had envisaged, all the large, double-mirrored doors stand open, reflecting the numerous crystal chandeliers and sconces, causing a deliberate optical illusion of space and light.
Smaller ceremonies such as the reception of new ambassadors take place in the '1844 Room'. Here too the Queen holds small lunch parties, and often meetings of the Privy Council. Larger lunch parties often take place in the curved and domed Music Room, or the State Dining Room. On all formal occasions the ceremonies are attended by the Yeomen of the Guard in their historic uniforms, and other officers of the court such as the Lord Chamberlain.
Since the bombing of the palace chapel in World War II, royal christenings have sometimes taken place in the Music Room. The Queen's first three children were all baptised here[23] in a special gold font. Prince William was christened in the Music Room; however, his brother, Prince Harry, was christened at St George's Chapel, Windsor.
The largest functions of the year are the Queen's Garden Parties for up to 8,000 invitees, taking tea and sandwiches in marquees erected in the Garden. As a military band plays the National Anthem, the Queen emerges from the Bow Room and slowly walks through the assembled guests towards her private tea tent, greeting those previously selected for the honour. Those guests who do not actually have the opportunity to meet the Queen at least have the consolation of being able to admire the Garden