Prince Andrew appears sombre as he is photographed during his weekly ride, marking his first public appearance since news surfaced about his brother, King Charles, battling cancer.
The Duke of York, who is currently facing controversy, looked disheartened as he trotted around a park wearing a navy blue jacket adorned with the insignia of the Grenadier Guards.
Accompanied by someone else on horseback, Prince Andrew was seen gesturing during their outing today.
The Duke of York's older brother, King Charles, was recently diagnosed with an unspecified form of cancer. Buckingham Palace announced on Monday that King Charles would be stepping back from royal engagements to focus on his treatment.
Royal commentators have suggested that the departure of Prince Harry and Meghan Markle, and the disgrace of Prince Andrew, could leave the palace struggling to find young royals to pick up royal responsibilities.
Prince Harry, 39, returned from the US this week to visit his father as news broke of the diagnosis, seen arriving at the royal residence on Tuesday to spend 'around 45 minutes' with his father.
Andrew, who remains an outcast and embroiled in scandal over his alleged connection to paedophile financier Jeffrey Epstein, had not been sighted since news broke of his brother's illness on Monday.
Other royals including Princess Beatrice have been seen out and about, with the princess leaving her residence at St James' Palace, next to her uncle's at Clarence House, early Tuesday morning, before returning later in the day.
Princess Eugenie, Andrew's daughter, published photos of her eldest son, August, on his third birthday today, two days after being spotted with Prince Harry's ex-girlfriend Cressida Bonas at a pub in Notting Hill.