prince george at kings cup regatta

Prince George and Princess Charlotte are the cutest sailors with granddad Michael Middleton

A family day out for the Cambridges!

Ainhoa Barcelona

The Duke and Duchess of Cambridge went head-to-head in a sailing regatta on Thursday, attending the King's Cup event on the Isle of Wight. While the couple's engagement had been in the diary for weeks, it was a welcome surprise to see Prince George and Princess Charlotte make an appearance with their maternal grandparents, Carole and Michael Middleton.

George, who turned six a couple of weeks ago, looked ever so sweet in a nautical outfit, donning a Breton-striped top and even a sailor's hat to boot. The future King, whose front teeth are noticeably missing, was pictured watching the races from a boat with his granddad Michael and a group of friends. Princess Charlotte was also spotted at the Cowes event, wearing a striped blue frock. 

Michael Middleton was on grandfather duties with Prince George

During the engagement, William and Kate took to the water to each skipper a boat, competing against one another and six other celebrity ambassadors: comedian John Bishop, adventurer Bear Grylls, England Women's footballer Fara Williams, television presenter Dan Snow, BBC presenter Katie Thistleton and Olympic champion rower Helen Glover.

MORE: Duchess Kate shows off Mustique tan in shorts 

Video: The Cambridges take part in the King's Cup regatta

The royals and the celebrities were each representing a charity that William and Kate support. The Duke sailed for Child Bereavement UK while the Duchess skippered a boat for the Royal Foundation.

George looked adorable wearing a sailor's hat

Their other charities that they supported were Centrepoint, London's Air Ambulance Charity's 30th anniversary campaign, Tusk, Action on Addiction, Place2Be and the Anna Freud National Centre for Children and Families. Bear Grylls' team won the first race, while William's team came third and Kate's group placed seventh out of eight.

Princess Charlotte was also in Cowes for the event

MORE: Beyonce's fans are convinced she's pregnant with baby number four

William and Kate hope the King's Cup regatta will become an annual event, increasing awareness of the benefits of sport, while also raising support and funds for their causes. The event is also giving the couple the chance to renew their sporting rivalry.

Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.