Prince William Laughs and Tells Knock-Knock Jokes Amid Kate Health Battle on Surprise Day Out

Prince William laughed and told knock-knock jokes amid his family heartache in a surprise London outing this morning.

The Prince of Wales, 41, looked in his element as he rocked up at a school after one of the students sent him an invitation, which he initially had to turn down.

William visited the West Midlands on Thursday, April 25, where he is carrying out engagements and visiting projects that are supporting people's mental health.

But he made sure that his first stop was the St Michael's School, where student-led initiatives are available to kids there to support their mental health.

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Marking World Mental Health Day back in October, student Freddie Hadley sent the prince a personal letter inviting him to the school. In the letter, Freddie explained that a group of boys aged 11-14 meet every week to develop ideas and projects that put a spotlight on male mental health.

He invited the future king to the school for the launch of a campaign last October, but unfortunately, the royal was unable to make it due to a prior engagement.

On arrival today, William congratulated Freddie for his efforts and told him: "Well done you, I'm here now. Your letter worked. I'm sorry I couldn't come to you in October."

The two then joined other children to record a segment for the school's radio station and the prince was asked to share a "dad jokes." He proceeded to tell knock-knock jokes, which he said were Princess Charlotte's favorite.

Today's engagements mark the second public outing for William since wife Princess Kate Middleton revealed she was undergoing cancer treatment. Last week, he returned to royal duties by helping to load a food truck and cooking in the kitchen at food distribution charity Surplus.

William’s break from duties coincided with an extended holiday from school for the couple’s three children, Prince George, 10, Princess Charlotte, 8, and Prince Louis, 6. During his time off, William was spotted attending a soccer match with George on April 11.

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A source exclusively told Us Weekly in March that William and Kate “wanted to wait to tell the world the news until their children were off school for the Easter break so they could have time to process the news [about her healthy battle] before the whole world was talking about [it].”

The couple has been keeping a low profile since Kate, 42, revealed her medical issues, although she and William took the time to thank well-wishers in March.

“The prince and princess are both enormously touched by the kind messages from people here in the U.K., across the Commonwealth and around the world in response to Her Royal Highness’ message,” Kensington Palace said in a statement. “They are extremely moved by the public’s warmth and support and are grateful for the understanding of their request for privacy at this time.”