London: 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.