Watch: Charles, William and Anne arrive on horseback for Trooping the Colour
Princess Anne has been praised for remaining perfectly poised atop her horse, Sir John, for a couple of hours during the Trooping the Colour parade.
The Queen's daughter, 71, joined her brother Prince Charles, 73, and nephew Prince William, 39, in riding down The Mall as part of the royal procession – which saw other members of the family, including the Cambridge children, travel by carriage.
Afterwards, the Princess Royal remained on horseback throughout the rest of the proceedings, leading to TV viewers to remark on her impeccable upright posture.
As Colonel of the Blues and Royals, she is very familiar with riding her horse for long durations of time but social media users noted how incredibly fit and healthy she appeared.
In a post on Twitter, the Daily Mail's royal correspondent Rebecca English wrote: "She’s 71 and been sitting ram-rod straight for almost the last hour."
Another commented: I know a lot of people do not agree with the pomp this weekend but you have got to admire Princess Anne riding her horse in the procession no carriage for her."
A third shared: ""I am so here for the way Princess Anne just rolls up on horseback like an absolute boss at 71."
Meanwhile, a fourth added: "How fabulous is Princess Anne #PlatinumJubilee."
In addition to the princess, social media users also shared their admiration for the Prince of Wales – a couple of years her senior – who was riding a horse called George.
One wrote: "Really need to give a shout out to Prince Charles and Princess Anne, both in their 70s and riding all morning in the heat and in those hot uniforms. RESPECT!"
Another commented: "Loving it...just watching Prince Charles and Princess Anne riding Horses. Awesome!"
A third shared that the pair, along with the Duke of Cambridge, had done the Queen and country "proud" with their "incredible display".
The princess – who is mother to Peter Phillips and Zara Tindall – has long been a passionate horsewoman and in her younger years regularly competed in high-level equestrian events.
She was named Sports Personality of the year in 1971, and then became the first British royal to compete in the Olympic Games in 1976.
The royal has also not shied away from putting in the effort in other areas of her life too, and was last year named the hardest working royal.
Her appearance, along with other members of the Royal Family, took place at the start of celebrations for the Queen's Platinum Jubilee, to mark the monarch's 70-year reign.