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Pop star Katy Perry might have a No. 1 single with her hit song, "Roar," but it is Britain's Prince George who has the real lion's roar, according to his dad.

"As you might have gathered, Catherine and I have recently become proud parents - of a baby who has a voice to match any lion's roar," Prince William, 31, said at a charity dinner in London Thursday evening with his wife, the Duchess of Cambridge.

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William's comparing his 2-month-old son, the third in line to the British throne, to a lion was appropriate for the evening's cause, a benefit dinner for outstanding conservationists hosted by the U.K.-based African wildlife conservation charity Tusk Trust.

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William, who is a royal patron of the charity, said this week he is ending his military career in order to focus more on his royal duties and conservation work. The cause is so near and dear to William's heart that it marked the first time the new parents had left their first child at home, a milestone he noted in his speech.

"This is actually our first evening out without him, so please excuse us if you see us nervously casting cheeky glances at our mobile phone to check all is well back home," William said.

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While the prince's comments about his son stole the show at the dinner, his wife, Kate, stole the red carpet in her first high-profile, official public appearance since giving birth.

Kate, 31, who gave birth to George July 22, looked stunning in a glittery floor-length, silver-sequined Jenny Packham dress that she paired with sparkly stilettos and an equally sparkly diamond bracelet.

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It was a much more glittery but equally glamorous look for Kate than in her first public appearance since Prince George's birth at the end of last month when she came as William's surprise guest at the kickoff of the 135-mile Ring O' Fire marathon in Anglesey, North Wales. The duchess at that time donned skinny jeans and a blazer that showed off her nearly back-to-normal figure.

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As Kate looked on, William took a more somber note at Thursday's awards dinner speech, noting that he is involved in conservation work, in part, to make the world a better place for George and any other children the couple might have.

"Like any new parents," William continued, "our thoughts inevitably turn to the world that our child will inherit. It is unfathomable to imagine a world in which children who have been born in the past couple of months may grow up in a world in which rhinoceros have ceased to live in the wild."

Last month, in a sit-down interview with CNN's Max Foster, Prince William joked that young George would be bathed in all-things Africa from early on, including his nursery.

"I'll have toy elephants and rhinos around the room," William said. "We'll cover it in, you know, lots of bushes and things like that. [We'll] make him grow up as if he's in the bush."