The Duke and Duchess of Cambridge are yet to meet the latest addition to the Royal Family, but are “absolutely thrilled” for Meghan and Harry.
William, 36, and Kate, 37, had a joint engagement at the Cutty Sark in Greenwich on Tuesday afternoon to launch The King’s Cup regatta.
The Duke and Duchess of Sussex welcomed a baby boy at 05:26 on May 6, 2019.
When asked about his new nephew, William said: "Obviously thrilled, absolutely thrilled, and obviously looking forward to seeing them in the next few days when things have quietened down.”
He joked: "I'm very pleased and glad to welcome my own brother into the sleep deprivation society that is parenting."
When asked if he had any pearls of wisdom for his younger brother as a father of three, William laughed and said: "Plenty of advice, plenty of advice, but no I wish him all the best and I hope the next few days they can settle down and enjoy having a newborn in their family and the joys that come with that."
The Duchess of Cambridge added: "It's such a special time, obviously with Louis and Charlotte just having had their birthdays, it's such a great time of year to have a baby, spring is in the air."
Kate continued: "As William said, we're looking forward to meeting him and finding out what his name's going to be, so it's really exciting for both of them and we wish them all the best.
"These next few weeks are always a bit daunting the first time round so we wish them all the best."
William and Kate are parents to George, five, Charlotte, four, and one-year-old Louis. They are also the uncle and auntie of Kate’s sister Pippa Middleton’s first child Arthur in October 2018.
The Prince of Wales is also yet to meet his new grandson. He and the Duchess of Cornwall are at the start of their four-day tour of Germany.
Speaking in Berlin, Prince Charles said: “We couldn’t be more delighted at the news and we’re looking forward to meeting the baby when we return.”
The Queen, 93, has also commented about the latest addition to the firm.
The Duke of Edinburgh, 97, made a rare appearance with the monarch at a luncheon for members of the Order of Merit on Tuesday afternoon.
Prince Philip retired from public duties in summer 2017. In January this year, he was involved in a car accident close to the Queen’s Sandringham estate in Norfolk.
His Landrover collided with a Kia at the junction of the B1439 where it meets the A149.
The duke was uninjured, but the driver of the Kia, a 28-year-old woman, suffered cuts to her knee while the passenger, Emma Fairweather, 46, sustained a broken wrist.
It was confirmed by Buckingham Palace that Prince Philip had surrendered his driving licence.
The Queen was quizzed about the latest addition to her family by one guest.
"Life is good for Your Majesty?" she was asked.
The smiling Queen replied: "Yes, thank you."
"Congratulations. Another great grandchild!" the guest added.
The Queen replied: "I know."
She was then asked how many she had before replying "eight".
A statement announcing the birth on Monday read: “The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, The Duke and Duchess of Cambridge, Lady Jane Fellowes, Lady Sarah McCorquodale and Earl Spencer have been informed and are delighted with the news.
“The Duchess’s mother, Doria Ragland, who is overjoyed by the arrival of her first grandchild, is with Their Royal Highnesses at Frogmore Cottage.”
The Duke and Duchess of Sussex and their baby son are expected to make their debut as a family of three on Wednesday.