The royal baby has arrived just over three and a half weeks before the royal wedding.
Prince Harry and Meghan Markle are due to tie the knot in Windsor in only 26 days' time on Saturday May 19.
The Duchess of Cambridge is expected to be attending but, with her baby son only a few weeks' old, she is not likely to stay for the entire celebration which will stretch into the evening and probably the early hours.
Her attendance is likely to depend on how she is feeling and how the baby is feeding.
When around one month old, the baby prince will be able to coo, gurgle and hum to express feelings, will have fully developed hearing and be able to focus a bit better but still only see around 30cm.
He may be able to hold his head up briefly but his neck muscles will still be weak.
Prince George and Princess Charlotte are tipped to be page boy and bridesmaid at the ceremony in St George's Chapel.
When the royal youngsters carried out the same duties for their aunt Pippa Middleton, Kate was on hand to guide them and keep them in line.
It is likely if Kate does attend, the baby will stay with the Cambridges' nanny Maria Teresa Turrion Borrallo.
The Duke of Cambridge is expected to be carrying out the role of Harry's best man.
Some 800 guests will gather in the gothic St George's Chapel to witness Harry wed American former actress Ms Markle, to whom he got engaged after a 16-month whirlwind romance after meeting on a blind date.