The Duke and Duchess of Cambridge took part in an on-screen sailing race as William cheekily urged his crew member to tip his wife out of the boat.
The couple’s competitive spirits were stoked as they sat in rival simulator boats and attempted to beat each other to the start line of a race.
But William displayed some rather underhand tactics, telling his helmsman to “ram” the vessel carrying his wife.
Pointing at the screen showing the boats’ progress, he said to seven-year-old Ethan, a pupil at Drapers Mills primary school in Margate, Kent: “Ram them, ram them! Aim for them. Tip them out.”
He later shouted over to Kate: “Are you sinking yet?”
Ten-year-old Sam, from the same school, was paired with Kate, and said: “It was tense, very tense, it’s the duke and duchess! The pressure builds – who wins, who loses.”
In just a few months’ time William, and Kate will go head to head in the King’s Cup Regatta to raise awareness and funds for eight of their patronages.
The regatta will be hosted by William and Kate on August 9 on the Isle of Wight, and will see the couple compete as the skippers of rival boats, part of an eight-strong field.
The couple launched the event at the Cutty Sark on Tuesday, the famous tea clipper ship in Greenwich, south-east London, and were joined by children and young people from eight charities which will be represented by the fleet.
Before the launch, they took the opportunity to congratulate the Duke and Duchess of Sussex on the birth of their son, with a “thrilled” William joking that he was happy to welcome his brother to the “sleep deprivation society”.
After struggling to cross the start line on time, and conceding a draw, the pair then met the heads of the charities of which they are patrons.
William spoke with CEO’s of Tusk, the London Air Ambulance Charity, Child Bereavement UK and Centrepoint.
The duchess met representatives from Place2Be, Action on Addiction, the Anna Freud National Centre for children and families and the Royal Foundation.
They later unveiled the King’s Cup which will be given to the winner of this year’s regatta – a historic trophy first presented by King George V at Cowes’ Royal Yacht Squadron in 1920.
Sir Keith Mills, chairman of the Royal Foundation, joked to the room as he invited the couple on stage: “I think they are both going to sneak in some practice between now and August.”
After leaving the Cutty Sark, the couple took time to say hello and shake the hands of some of the crowd of well-wishers gathered outside.
William and Kate hope the King’s Cup will become an annual event, bringing greater awareness to the wider benefits of sport, while also raising support and funds for their causes.
The duke trounced his wife when they competed in a dragon boat race in Canada in 2011, but Kate got her revenge three years later when she won a sailing event in Auckland during their tour of New Zealand.
William took the honours again during a visit to the German city of Heidelberg in 2017, when he was victorious in a riverboat race against his wife.