LONDON (AFP) - Prince George was taken by his father to the clinic where his little sister was born on Saturday, in a rare appearance for the third in line to the British throne.
Prince William carried the toddler, who wore a blue jumper and shorts, and both future kings waved to the crowds, with William directing his son.
They then headed into the hospital, with a puzzled-looking George continuing to gaze over his father's shoulder at the banks of cameras.
William and his wife Kate have jealously guarded their son's privacy from the media and last year threatened to take a paparazzi to court for taking picture of the toddler being taken out to play in a park.
The boy has been seen in public just three times.
The first was on July 23, 2013 when he was shown to the world wrapped in a white blanket in the arms of his radiant parents - aged just 27 hours.
George's second public engagement came three months later at his Christening, followed by a family tour of Australia and New Zealand in April 2014 where the chubby-cheeked royal stole the show.
In New Zealand, he was seen playing with other babies in the residence of his great-grandmother Queen Elizabeth II's governor-general.
On a visit to a Sydney zoo, he showed particular interest in a bilby - an endangered animal.
Besides these appearances, the royals have occasionally released official photographs of the young prince.
George has been seen in the garden at Kate's parents' home after the birth; sat with the family in a Kensington Palace window ahead of his first overseas tour; playing with butterflies at the Natural History Museum to mark his first birthday; and sitting on the Kensington Palace steps for Christmas 2014.