The Queen and the Duke of Edinburgh attended the Trooping the Colour ceremony in London on Saturday.
The Duke turned 91 last Sunday. Wearing a red military jacket with a blue sash and gold epaulettes, he looked alert and in good spirits.
It was his first major public appearance since leaving hospital, where he had been treated for a bladder infection.
Thousands of people watched the Prince of Wales and the Duke of Cambridge ride to the ceremony at Horse Guards Parade.
The Queen and Prince Philip rode in a glass coach down the Mall to the ceremony.
The coach, built in 1881, was first used by the Queen and Duke on their wedding day when they travelled from Westminster Abbey to the palace on 20 November 1947.
The Queen, wearing her Brigade of Guards brooch, took the royal salute as senior members of the royal family looked on.
The Colour being paraded on Horse Guards this year is the flag of the 1st Battalion Coldstream Guards.
More than 1600 officers and soldiers took part in the display, with 240 horses and 290 bandsmen who marched and played as one.
The Queen, who celebrated her Diamond Jubilee last weekend, has attended the Trooping the Colour every year except in 1955, when it was cancelled because of a national rail strike.
The BBC reports the parade has marked the Sovereign's official birthday since 1748. The Queen's actual birthday was on 21 April, when she turned 86.