"He is looking forward to being a dad. He's very excited about it," says Seyi Obakin, chief executive of the charity Centrepoint, whose aim is to help homeless young people.
Obakin spent a few hours with the prince, 30, when he secretly stopped by Centrepoint's Bruce House in London earlier this week. Prince William – who is a royal patron of the charity – spoke with residents who are learning to be entrepreneurs and other skills so they can be successful in their communities.
"They talked about music, movies, fun things," Obakin tells PEOPLE. "He has a genuine concern for how life is like for them as the country is going through this recession."
Some of the young people who are benefitting from the charity have started a business selling healthy smoothies and chocolates, which William sampled during his low key visit.
"They had some products there that he was very happy to indulge in," Obakin says.
William played Ping-Pong with a group of residents – "He just picked up a [paddle] and joined them," Obakin says – and watched as other young people played with a soccer ball.
Making an under-the-radar visit like this is just the sort of trip his mother, Princess Diana, would quietly make to different charitable organizations, taking her sons William and Prince Harry along when they were boys.
"He's carrying that [tradition of service] on," Obakin says. "He appreciates that if he did this kind of thing in public he wouldn’t get the same quality of conversation he wanted with the young people."
Harriet Armstrong / Centrepoint