The Duke and Duchess of Sussex have joined the Queen for the Trooping the Colour parade to mark her 92nd birthday.
Prince Harry and his new wife Meghan, who married last month, arrived as part of the carriage procession.
Prince Philip, who retired from royal duties last year, did not attend the military parade. He turns 97 on Sunday.
Field Marshal Lord Guthrie fell from his horse during the parade and has been taken to hospital.
Lord Guthrie, 79, is the former head of the Army and then Chief of Defence Staff, the UK's most senior military officer.
Meanwhile, a 51-year-old woman has been arrested for a public order offence after an item was thrown towards the procession.
She is currently in custody at a central London police station, the Met Police said.
The Duke and Duchess of Sussex joined senior royals including Prince Charles and the Duke and Duchess of Cambridge for the event in London.
Large crowds of spectators gathered to watch Saturday's ceremony, which saw about 1,000 soldiers march to Horse Guards Parade in Whitehall.
Afterwards, the Royal Family appeared on the balcony in Buckingham Palace to watch an RAF flypast which included a display from the Red Arrows.
The Duke and Duchess of Cambridge's young children, Prince George and Princess Charlotte, looked out over the crowds, standing next to Savannah and Isla - the Queen's great-granddaughters.
The Duchess of Cornwall and Duchess of Cambridge arrived together as part of a carriage procession along the Mall.
They were followed by the Duke and Duchess of Sussex and the Queen's cousin, the Duke of Kent, in a second carriage which was greeted by cheering crowds.
The Countess of Wessex, her daughter Lady Louise and princesses Beatrice and Eugenie travelled in the third carriage.
The Queen, wearing a powder blue outfit, arrived in a separate procession.
Trooping the Colour has commemorated the birthday of the sovereign for more than 250 years and also functions as a display of army drills, music and horsemanship.
There had been fears that Field Marshal Lord Guthrie's fall from the horse may have altered timings for the RAF flypast, but the Royal Family's balcony appearance went ahead as planned.
Who is Field Marshal Lord Guthrie?
Field Marshal Lord Guthrie of Craigiebank is a former SAS commander who was head of the British Army until 1997 and then chief of defence staff until 2001.
Born in 1938, Lord Guthrie attended military training college in Sandhurst and went on to serve with the Welsh Guards in Cyprus, Germany and Northern Ireland.
During his time with the SAS he served in Aden, the Gulf, Malaysia and East Africa.
As commander of the Hong Kong British forces he played a high-profile role in Britain's withdrawal from Hong Kong in June 1997.
Among the soldiers who took part was Guardsman Charanpreet Singh Lall, a 22-year-old Sikh from Leicester, who became the first soldier to wear a turban in the parade's history.
The Queen, who celebrated her 92nd birthday on 21 April, recently had surgery to remove a cataract from her eye.
She and 7,500 guests watched the ceremony - which will this year parade the flag of the 1st Battalion Coldstream Guards - from a dais in Horse Guards before inspecting the guardsmen.
Among the guests was Defence Secretary Gavin Williamson and US Defence Secretary General James Mattis.
The Queen has travelled every Trooping the Colour of her reign except in 1955 when it was cancelled because of strike action.
During her reign The Queen has attended Trooping the Colour every year except 1955 when it was cancelled because of the general strike. Here, the then Princess Elizabeth accompanies King George VI on the way to Trooping the Colour in 1947. pic.twitter.com/rzKvP1clV5— The Royal Family (@RoyalFamily) June 9, 2018
At the scene: Royal correspondent Sarah Campbell
The sun shone and the crowds (most of whom seemed to be tourists) got their glimpse of the senior royals.
The first big cheer was not surprisingly directed at the carriage containing the new Duke and Duchess of Sussex (Harry and Meghan).
The Household Cavalry sparkled in the sunlight and the 41-gun salute boomed around the capital.
On the palace balcony - perhaps keen not to steal the limelight, the newlyweds stood at the back almost completely out of sight.
Princess Charlotte was more than happy to be the focus of attention - clapping enthusiastically as the various aircraft flew overhead.
This is one of the key royal events on the calendar - with the balcony view providing the family snapshot of the year.
Afterwards, the King's Troop Royal Horse Artillery fired a 41-gun salute in Green Park to mark the official birthday.
The Duchess of Sussex wore an off-the-shoulder dress designed by Carolina Herrera and a hat by milliner Philip Treacy. The Duchess of Cambridge wore an Alexander McQueen and a hat by Juliette Botterill.
Later this month, the Duchess of Sussex will accompany the Queen on a royal engagement to officially open a theatre and bridge in Cheshire.
It will be the first time the duchess has joined the Queen for an event without her husband.
The couple attended a garden party at Buckingham Palace on 22 May for their first royal engagement as a married couple.