WATCH: Kate Middleton Packs a Mean Punch for the Best Reason

A video posted by Kensington Palace (@kensingtonroyal) on May 16, 2016 at 3:34am PDT

Kate Middleton is taking a jab at mental illness.

Middleton showed off her right hook at an event for mental health campaign Heads Together in London on Monday, PEOPLE reports. She attended alongside her husband and brother-in-law, Princes William and Harry.

Three-time world champion boxer Duke McKenzie was in attendance and sang Middleton's praises, saying Kate "couldn't wait to get the gloves on and had a wicked punch."

Though it's Prince Harry, he said, who hits the hardest. "Harry's a banger — make no mistake about it. He runs like a Bentley or a Rolls Royce — he purrs quite well. I've boxed my whole life and he's got a fair punch on him."

The Duchess has the royal brothers beat on her technical prowess, however.

"She's better than the pair of them because she's more technical. Ladies don't go for power. They rely on speed and technique and that generates your power. She was better than the pair of them technically, hands down," McKenzie said.

McKenzie complimented the trio on putting their heads together to create such an event.

"It's great that they've put their time and effort to this. This is going to be a success. It's going to highlight so much and make so many people much more aware of mental health problems," he said. "They wouldn't have put their names to this event if it was going to fail. It shows how serious they are about it."

The three royals met with a group of eight charities that make up the Heads Together campaign at the launch event in London, after announcing the charity in April.

It's their hope that the campaign will encourage people to feel comfortable with their mental health, support friends and family members who might be struggling with mental health issues and "ensure stigma doesn't prevent people seeking the help they need."

The campaign is the biggest project they've put together and includes the areas they have already started to work on individually — Middleton with children's mental health, Prince William with shining a spotlight on male suicide and Prince Harry with highlighting the invisible wounds of war, as he demonstrated at this year's Invictus Games.