She joined members of her family and senior figures for the annual ceremony of pomp and pageantry staged in the grounds of Windsor Castle.
Philip is convalescing at the Castle after he left the London Clinic this morning following exploratory abdominal surgery more than a week ago.
The Queen flanked by Prince Charles, left, and Prince William en route to the chapel in Windsor today
The service was preceded by the procession of members of the Order of the Garter - one of the highlights of the royal season.
In a touching change with tradition, the Queen, who would normally walk with Philip, was flanked by the Prince of Wales and Duke of Cambridge.
With Charles on her right and William on her left, she smiled as she walked towards St George’s chapel for the service.
Wearing their blue velvet robes and black velvet hats with white plumes of heron and ostrich feather, the Royal Garter Knights walked past the thousands of spectators gathered in the grounds of the castle.
With the Duke of Edinburgh convalescing after
being discharged from hospital this morning, the Queen was instead
flanked by her son and grandson
Other members of the monarchy who are
also Royal Knights or Ladies of the Order and took part in the
procession were the Princess Royal, Duke of York, and the Earl of
Wessex.The Duchess of Cornwall and Countess of Wessex watched the procession from the vantage point of the Galilee Porch at St George’s Chapel as their partners processed past.
Founded by King Edward III in 1348, the Order of the Garter is the last remaining honour to be given at the discretion of the sovereign and is awarded to those who have contributed to national life or have served the Sovereign personally.
Every knight is required to display a banner of his arms in St George's Chapel at Windsor, together with a helmet, crest and sword and an enamelled stallplate and carries the letters KG after their name for life.
William was officially invested in the order in 2008 in a private ceremony at the castle Throne Room, accompanied by his father and grandfather.
The knights today enjoyed an elaborate luncheon in the castle's Waterloo Chamber before making their way to the chapel for the religious service of installation for new members.
More than 7,000 specially-invited members of the public cheered on the party, who were proceeded by trumpeters and elaborately costumed heralds as well as the 14 Officers of Arms, each bearing ancient titles such as the Rouge Dragon Pursuivant and the Maltravers Herald Extraordinary.
The Queen travelled from the ceremony in a carriage with Camilla and Charles with two liveried footman at the rear
Camilla attended the Order Of The Garter in a powder blue suit with feather-trimmed hat
They drove past squadrons of the Household Cavalry's Life Guards and Blues and Royals who lined the route.
Following soon behind was Edward and Sophie, sitting opposite William and Andrew in their carriage.
The Countess wore a hat perched on the side of her head and she hung onto the brim as the wind began to pick up.
William was photographed appearing to stick his tongue out as he went past.
The crowds cheered as they royals passed and they were soon joined in the Castle by members of the congregation for afternoon tea.
The traditional Garter hat is trimmed with heron and ostrich feathers
The Order welcomed a new Garter Knight, Air
Chief Marshal the Right Honourable Graham Eric who was Invested by the
Queen in the Garter Throne Room and installed as a Knight during the
service in St. George's Chapel today
Happy to be going home: Prince Philip smiles and waves as he left the London Clinic 11 days after an abdominal operation
New appointments are announced on St George’s Day but the chivalric and installation ceremonies take place on the Monday of Royal Ascot week, known as Garter Day.
The former head of the UK’s Armed Forces Air Chief Marshal Lord Stirrup was invested by the Queen in the Castle’s Garter throne room, and later installed as a Knight Companion during the service in St George’s Chapel.
His appointment brings the total number of Garter Knights to 22 out of a maximum of 24.
The two vacancies were created by the deaths of Viscount Ridley and Baroness Thatcher.
Recipients of the honour are chosen because they have held public office, contributed to national life or served the sovereign personally.
The appointment of Knights of the Garter is in the Queen’s gift and is made without consulting ministers.
Other members of the order include former prime minister Sir John Major, Lord Phillips of Worth Matravers, a past president of the Supreme Court, and Admiral Lord Boyce, a former head of the UK’s Armed Forces.
During the service hymns were sung and prayers said for the Order of the Garter.
Founded in 1348 by Edward III, the Garter is the senior British order of chivalry awarded by the sovereign for outstanding public service and achievement.
Originally it served the double purpose of bringing together the sovereign and 25 senior knights who were the country's military leaders as well as establishing a new fellowship in religious worship.
The patron saint of the Order is St George.
The Order's emblem is a blue ribbon or garter worn by men below the left knee and by women on the left arm.
The Garter - also incorporated in the Royal Coat of Arms - bears the famous legend "Honi Soit Qui Mal Y Pense" ("Shame on him who thinks this evil").
The motto could have referred to critics of Edward III's claim to the throne of France.
Modern scholars have cast doubt on the tradition that the order was inspired by a garter dropped by Joan, Countess of Salisbury, at a ball in Calais, which the King retrieved and wore on his leg.
Although 14th-century knights did wear ladies' favours when jousting, it seems more likely that the garter was a strap used to attach armour.
Other items of dress worn by modern Garter Knights include a blue velvet mantle or cloak with the badge of the order on the left shoulder, a vestigial hood of red velvet worn over the right shoulder, and a black velvet hat garnished with white feathers.
Every Knight or Lady of the Order is required to display a banner of his or her arms in St George's Chapel, Windsor, together with a helmet, crest and sword, and an enamelled stall-plate.
The modern pattern of the Garter ceremony dates from the order's 600th anniversary in 1948 when George VI revived formal installation of new Knights for the first time since 1805.
In 1987 the Queen opened the order to non-royal women and the first to be admitted was Lavina, Duchess of Norfolk in 1990.
If there are new Knights or Ladies of the Garter, the Queen formally invests them with Order's insignia in the Throne Room of Windsor Castle, followed by lunch in the Waterloo Chamber and the Garter procession to St George's Chapel.
