Middleton, 28, cut a stylish figure in an Alice Temperley dress on her way past photographers, and earned high marks from seven young patients she and Prince William met during the interval of the charity Christmas fundraising concert in Norfolk, England.
"They took a genuine interest in what I'd been through and the operation I had," Rosie Van Raalte, 16, from Little Melton, Norfolk, says in a statement. "The conversation flowed really well, and they made me feel relaxed, as I was really nervous before I saw them. Once I started talking, I relaxed and even forgot that I was talking to a Prince!"
Lucy Smith, 23, from Norwich, added, "We spoke about my treatment and how much the Teenage Cancer Trust had helped me. They were both very friendly, relaxed and down to earth, and I enjoyed meeting them."
A third patient, Adam Brown, 22, from Roughton, Norwich, added his praise, saying, "The Prince asked me what age I was when I was first diagnosed and what my ongoing treatment is like. They were both very pleasant and nice to talk to."
The concert helped raise $54,000 for the Teenage Cancer Trust's local campaign to build the first specialist cancer unit for young people 13-24 at Addenbrooke's Hospital in Cambridge.
William and Kate, who are due to be married on April 29, sat together to watch the Christmas Spectacular, which included singing, dancing, magic and ventriloquism.
"We feel incredibly privileged that both Prince William and Miss Middleton gave up their valuable time and lent their support to Teenage Cancer Trust's fundraising appeal," Simon Davies, the group's chief executive, said in a statement.