"We are very excited," says Chloe Crookes, 9, from the local St. Aloysius Primary School, one of a noisy group of kids waving flags at the city's famous university, saying "Hello" in Chinese and shouting congratulations.
"We wanted to see her but she's having a baby," Crookes adds.
Asked what she thought about the news when they were told by their teacher, she says, "I was surprised because she had a baby already."
Kate, 32, was supposed to be with William, also 32, at this event – for the engagement of a new Dickson Poon University of Oxford China Centre – but palace officials had to reveal she was pregnant when it was apparent she would be too unwell to attend. She has severe morning sickness and is being cared for by doctors at home at Kensington Palace.
William also got some gifts.
Little schoolgirl Bethlilly Barton, 5, presented him with a toy swan.
"I told him it was for baby George," she tells PEOPLE.
She had a small bouquet of flowers for Kate (who she didn't know was expecting). The flowers were getting the attention of a bee, which attentive William swatted away as he crouched down to chat with her.
"The bee was on the flowers to get some honey," Bethlilly says. "Bees like honey."
Her father Stuart McPherson said of the pregnancy, "It's wonderful news." And he predicted William will be a great second-time dad.
"He was really great with the children," he tells PEOPLE. "It was great to see."
In a lineup of dignitaries at St Hugh's College, William was all smiles and chatted with the high sheriff of Oxfordshire Tony Stratton who congratulated him – and said he's likely to be one of many doing so today.
"That's very kind," William told him. "I am sure it will be a feature of the day."
Inside the new China Centre, William was meeting designers and building contractors who worked on the project, donors and academics.
William impressed head teacher Tom Walker with his interaction with the children.
"He was lovely, so relaxed," Walker tells PEOPLE. "He engaged with them really well."