Prince Harry has revealed he already "can't imagine life" without son Archie - but admitted the baby had kept him up last night.
The Duke of Sussex, 34, who welcomed son Archie with Meghan last Monday, opened up about life as a new father as he spoke to patients and their families at Oxford Children's Hospital today.
Mother-of-two, Ida Scullard, whose 3-year-old son Emmett is in remission, revealed the prince had struck up a conversation after seeing she was cradling her 10-month-old daughter.
"Harry asked me if she [my baby daughter] was over the stormy period as babies are supposed to be grumpy for the first 10 weeks," Scullard said.
"He said he's getting used to the baby and how Archie has fitted into family life. He said he just feels part of the family and he can't imagine life without his son."
The Duke told another patient how his baby had kept him up last night.
Later that afternoon the Duke of Sussex was commended for keeping Princess Diana's legacy alive as he visited the OXSRAD Disability Sports and Leisure Centre, which his late mother was pictured opening in similar touching pictures dating back to 1989.
Alan's widow Julia, who had been there when Diana launched the centre in 1989 was there to greet Prince Harry.
Speaking about her memories of Diana's visit, she joked: "The main thing I remember when Diana visited was that she said, 'what's through there' and then went into the gents lavatories!"
The Duke was then given a tour of the centre, starting with an exercise session.
He met a service user called Charlotte Robinson who was trying to compete in a challenge using yellow and red cones, which he helped push towards her.
Harry cheered with the helpers when she succeeded.
Next, he greeted Isobel Warburton, who has cerebral palsy and uses a special walking frame at the centre to keep her joints active. He asked what she liked best, to which she replied, "walking!" She told him that she had been coming to the centre for four years. Using the centre helps her to stay mobile and has helped her to make lots of friends.
Harry asked her, "Do you love it here? Who is your favourite physio?". She replied it was a physio called Harry, to which he laughed.
"Is he the one with the big beard, he knows we're talking about him!"
Realising he had been pointing to another physio named Dave, he worked out who the "other" Harry was and congratulated him.
Afterwards, Harry moved on to watch Rebound Therapy, where service users were using trampolines to help their mobility.
He knelt down to speak with Katie Goodwin, 38, who has cerebral palsy and finds that trampoline work helps with tight muscles. She asked how Archie was doing, to which Harry replied with sincerity: "He's doing really well. Thank you."
Remarking on her glittery socks, Katie said, "I put them on especially for you Harry," which made him roar with laughter.
Harry joked before moving to the next person: "You've had a chance to catch your breath - now you need to carry on!"
Katie said afterwards: "I have met Diana before - when I was 11 she came to my school. She said that I had lovely hair and a lovely smile. To meet one of her sons 27 years later is so amazing. When I told Harry I had met her he was really touched and said, 'that's lovely!' I said how lovely it was that he - and also William - were keeping her legacy alive. He said, 'we try.' Harry seemed so natural. I thanked him for being here. I found it quite emotional."
He spoke to Alistair Hoddy who was exercising on a beanbag placed on the trampoline, remarking, "This is a great beanbag. Is it your beanbag or have you borrowed it?"
He remarked on the simplicity of it, in an age when "we think technology can solve everything."
Looking around him, Harry added: "I love this place. It's fantastic."
Prince Harry spent time chatting to youngsters on the Kamran Jabble cancer ward, named after a former patient.
Emmett, three, of Aylesbury, Buckinghamshire, is in remission after being diagnosed with testicular cancer when he was just two years old.
He was at the ward with his mother and 10-week-old sister Ida.
The Duke of Sussex brightened up patients' days by making balloon animals and playing with a dinosaur toy set on the hospital floor.
The royal appeared in good spirits as he arrived for the visit earlier this morning, crouching down to chat to children who had waited to greet him outside.
He was presented with a teddy for Archie by former patient Daisy Wingrove, 13, who smiled as she handed over the gift.
The teenager appeared to say something that tickled the Duke as he chuckled happily during the conversation.
Harry is touring the hospital - a purpose-built centre for the treatment of children and young adults based at the John Radcliffe hospital site - to highlight the important work it does.
During the visit, the duke met children and young people receiving treatment, and the staff caring for them, as well as supporters of Oxford Hospitals Charity.
He visited teenagers on a ward specifically tailored to the needs of young adults and meet 13-year-old Mikayla, a WellChild award winner, who previously met the duke at the WellChild Awards in 2016.
Before leaving, Harry visited the hospital's school to meet students, taking lessons while undergoing treatment, and their teachers.
Finally, the duke visited Barton Neighbourhood Centre, a hub for local residents which houses a doctor's surgery, food bank, cafe and youth club.
Harry got a pop star's reception from hundreds of residents on a housing estate who turned out to see him visit their neighbourhood centre today.
So many children had made him cards congratulating him on the birth of his son, Archie, he struggled to carry them and turned forlornly to aides, asking them to take huge piles off him after pupils from three schools handed them to him individually.
Harry, 34, accepted the congratulations of well-wishers, including mother Fatma Sheikh, 43, a mother of three, who told him: "You done good."
Sheikh, originally from Tanzania, said after meeting him: "I asked him how Archie was and he said he is doing well. I asked him if Meghan was well and he said yes, she is fine."
The proud new dad seemed overwhelmed by one present for Archie when he visited Barton Neighbourhood Centre, which serves 5,000people on the tough Barton estate in Oxford where social deprivation levels are high.
Claire Waldron, who works as a caretaker and cleaner at the centre, had made Archie a gift from a varnished piece of rock that she had decorated with his name.
Claire, 38, decorates large stones and rocks and hides them for children to find on treasure hunts. She calls them kindness stones or rocks. When it was suggested to Harry that he could hide the rock in the garden at Frogmore House for Archie to find when he is older, he seemed taken with the idea.
"Can you imagine him finding it and saying: "I've got a rock and it's got my name on?" he said, already imagining his eight-day-old infant as a little boy. "Thank you very much. I love that."
He hugged Claire and patted her warmly on the back and mouthed 'thank you' again before he left the room.
Harry cut a cake and unveiled a plaque to mark a £1 million refurbishment of the centre funded partly by money from a new housing development and the rest by Oxford City Council.
Inside in the basement he watched teenagers taking part in a bridge-building exercise as part of a course designed to help young people develop leadership skills run by the charity Thrive Teams.
As two lads nearly lost their balance using a bread crate and a short, narrow plank to get over an imaginary river, Harry, no doubt a veteran of such exercises during his 10 years in the Army, cheered them on. 'You've got to hold on to each other. That's the point,' he said.
Upstairs on the ground floor, he met volunteers from The Oxford Food Bank, showcasing some of the 1 tonne of food they distribute each day to deprived communities such as Barton.
Their food, which would otherwise go to waste, is collected from supermarkets and wholesalers. They come to Barton three times a week and distribute supplies to the poorest families and provide ingredients for the neighbourhood centre's cafe to supply low cost meals fiecas little as £2 to the estate's residents.
"You collect 400 tonnes of food per year that would have been wasted?" Harry asked, before complaining about the waste caused by food manufacturers using sell-by-dates and plastic packaging.
"If you bought things loose, you wouldn't know the dates, would you?" he said. "Can you tell me why anyone would want to put bananas in plastic bags?"
He suggested Britons needed to change their mindset to reduce the amount of packaging around food and told Cathy Howard, the food bank manager: "It's amazing what you guys are doing."
In the next room, local residents were enjoying a cheap meal made from food bank produce.
Harry went around the room, chatting to everyone.
One diner, Susie Wilkes, 48, asked him: "Are you not joining us for lunch?". "I would have done but I wasn't invited,'" Harry replied.