The Duke of Cambridge has welcomed his brother to “the sleep deprivation society that is parenting” after the birth of the Duke of Sussex’s son.
Prince William said he was “absolutely thrilled” for Prince Harry and Meghan, whose child was born at 05:26 BST on Monday.
The father-of-three added he looked forward to seeing the new parents “when things have quietened down”.
The Prince of Wales said he was also “delighted” by the birth.
Prince Charles and the Duchess of Cornwall were congratulated and given presents during a four-day trip to Germany.
Shortly after he arrived in Berlin, he said: “We couldn’t be more delighted at the news and we’re looking forward to meeting the baby when we return.”
Before a private meeting with the prince, German President Frank-Walter Steinmeier presented him with a teddy bear wearing blue clothes.
Later, when members of the public in Berlin offered their congratulations on his fourth grandchild, Prince Charles said: “Thank you, I’m collecting a rather large number of them.”
Prince William was at an event at the Cutty Sark in Greenwich, London, with the Duchess of Cambridge.
He said: “I’m very pleased and glad to welcome my own brother into the sleep deprivation society that is parenting.”
“I wish him all the best and I hope in the next few days they can settle down and enjoy having a newborn in their family and the joys that come with that,” he added.
The Duchess of Cambridge said: “We’re looking forward to meeting him and finding out what his name’s going to be… these next few weeks are always a bit daunting the first time round so we wish them all the best.”
She 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.”
Harry and Meghan’s son, who has not been named yet, is seventh in line to the throne, behind the Prince of Wales, the Duke of Cambridge and his children – Prince George, Princess Charlotte and Prince Louis – and Prince Harry.
He is the Queen’s eighth great-grandchild.
In Berlin, the Duchess of Cornwall visited a clinic for victims of domestic violence, where staff members gave her a onesie with German art on it and a balloon for the baby boy.
The duchess said: “As soon as we return I will deliver it to them, direct from Germany.”
The royals’ words followed messages of congratulations from around the globe.
Former US First Lady Michelle Obama said she and Barack Obama were “thrilled” at the news, while Meghan’s former colleague Patrick J Adams sent love to the “incredible parents”.
Speaker John Bercow opened the House of Commons on Tuesday by saying: “I am sure the whole House would want to join me in sending their Royal Highnesses the Duke and Duchess of Sussex our warmest congratulations on the birth of their son.”
Meanwhile celebrations were under way in the town near to Frogmore Cottage – the Sussexes’ home on the Windsor Estate.
Local fans dressed up in their finery to mark the occasion while Windsor’s shop window displays were crammed with royal merchandise.
It has not yet been confirmed where the baby was born, but it is believed Meghan gave birth in hospital rather than at home.