Guards stood to attention as her Jaguar moved down the driveway just before 3pm, 24 hours after a poignant minute’s silence was held.
She looked to be wearing a headscarf, as she often does when at the wheel.
It is not clear where she was heading, but she may have been setting off to take her dogs for a walk.
Before the funeral the Queen was seen driving the same car, reportedly to take the puppies on a sombre stroll.
She was thought to be heading to Frogmore Gardens, where her mother is buried and where she and Philip will eventually be laid to rest.
Princess Eugenie and her husband Jack Brooksbank were also seen driving out of the grounds moments before the Queen, a day on from the emotional service.
Yesterday they joined the Queen and 27 mourners to say goodbye to the Duke of Edinburgh – who died on April 9 aged 99.
It was a deeply personal service, with details decided by the Duke before his death, and watched by millions across the globe.