Carole and Michael Middleton's visit to the Lindo Wing of St Mary's hospital in Paddington, central London, came as it emerged that mother Kate, father William and baby Prince Cambridge were not expected to leave the hospital until much later tonight or even tomorrow morning.
Crowds remained parked outside the hospital in anticipation of the first glimpse of the new prince, with the world's media waiting with cameras at the ready to snap the first pictures of the royal heir.
William is on a two-week paternity leave from his job as a Royal Air Force pilot based on Anglesey in Wales and spent the night at the hospital.
He is expected to pose for the customary photographs with Kate and the child on the steps of the hospital as they leave for home.
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After what was labelled as the "Great Kate Wait" is over, the media speculation is now centred around not only the name of the third in line to Britain's throne but also how he would be secured into a child seat for his journey from the hospital to home, expected to be an apartment in Kensington Palace.
The birth after a labour of less than 12 hours brought relief not only to the nation but also to the rows of television news anchors camped on the pavement outside the Lindo Wing for days.
Under the blistering heat of the hottest July day in London since 2006, representatives of 150 television stations and some 300 photographers broke into cheers as the official announcement was made yesterday evening.
The arrival of a boy postpones for another generation any anti-sexist statement that a daughter to William and Kate would have made by overturning the rule of primogeniture.
Meanwhile, celebrations carried on across Britain with church bells and gun salutes.
Trafalgar Square in London will be lit blue for a week and the traditional Guard of Honour at Buckingham Palace played "Congratulations" to mark the birth.
The new parents have pledged support for a charity supporting St Mary's Hospital in celebration of their son's birth.
They are backing Imperial College Healthcare Charity, which raises money for research and studies designed to improve services to St Mary's and four other hospitals constituting Imperial College Healthcare NHS Trust.