The Queen arrived at the five-day event today, dressed casually and ready for a day of fun.
Last month, Prince Philip, 96, had hip replacement surgery after his physicians deemed it necessary after a painful struggle with osteoarthritis.
His latest outing is perhaps the strongest indication yet that Prince Philip will in fact attend his grandson Prince Harry's wedding on 19th May.
The Duke, who retired from royal duties a year ago, was last seen on April 13, when he left the hospital waving to the cheering crowd from the auto.
His daughter-in-law, Sophie Countess of Wessex, and granddaughter, Lady Louise Windsor, 14, joined him at the event.
More recently Lady Louise has taken up carriage-driving, a past-time beloved of her grandfather, Prince Philip, 96, who is credited with popularising the sport in Britain.
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First came a Thursday tweet featuring a clocktower smeared in the same shade of pink, with the arms pointing to the time 5:14. There is so much on the table that this year's E3 press conference will perhaps be the biggest for the makers of Fallout .
Queen Elizabeth had a great morning, with her horse winning in the class she watched.
Arriving shortly afterwards was the Queen's cousin and his wife Prince and Princess Michael of Kent.
Princess Michael certainly considered it a day to remember and could be seen snapping photographs on her mobile phone from the rear of the carriage.
The show, now in its 75th year, is held annually in the private grounds of Windsor Castle and is the only event of its kind in the United Kingdom to host global competitions in show-jumping, dressage, driving and endurance.
She was pictured yesterday sharing a joke with a male companion as she took in the show which is held in the castle's private grounds.