Prince William admitted to breaking a royal rule today as he visited a world-famous beach in Cornwall.

The prince, who is also the Duke of Cornwall, paid a visit to Fistral Beach just hours after his estranged brother Prince Harry was in the UK for an appearance at St Paul's Cathedral for his Invictus Games. During the visit, William said he was desperate to get his wet suit on and get out in the ocean, but stayed suited and booted as he was on official duties.

However, he made one little boy's day as he secretly signed his plaster cast and told him: "Shhh, don’t tell anyone. I'm not meant to do that!" Phoenix Kanes, nine, cheekily stopped the prince and asked if he would sign the plaster cast on his broken arm.

William signs the plaster cast of a young boy on the beach (
Image:
PA)

William smiled good-naturedly and agreed but told the youngster he wasn't meant to do it. Last year at the Chelsea Flower Show his wife Kate revealed she wasn't allowed to sign her name on some drawings done by school children saying it was one of those rules - although she did do a little drawing for them. King Charles has also been known to turn down such requests, once politely telling fans, "Sorry, they don't allow me to do that."

Elsewhere on the beach, William met representatives from local organisations who are working to promote safety in the sea and across the beach area, ahead of the forthcoming summer months. William spent several minutes chatting to staff and children from Holywell Bay and Newquay Surf Life Saving Clubs which trains and supports volunteers to save lives and prevent drowning in open water.

William takes part in an impromptu game of beach vollyeball (
Image:
PA)

The Prince, who regularly holidayed with his brother, Harry, in Cornwall when they were younger and can surf well by all accounts, said looking around the beach and turquoise water: "It brings it all back. I want to put on a wetsuit and get out there now!"

He also stopped to speak to children learning life-saving techniques as part of the Holywell Bay Surf Life Saving Club - and although beach volleyball hadn’t been part of his planned activities for the day, the heir to the throne couldn’t resist stopping and asking if he could join in.

He was handed the ball and showed it wasn’t his first time playing as he aced three killer serves. He chivalrously decided to hand the ball to another member of his team after that and played in the back row. Crowds gathered keen to grab a selfie with the prince, which he happily complied with. He was also touched to be given a home-made card of Truro for himself and Kate by Harriet Fox-Furness, 11.

William speaks to a group of surfers (
Image:
Getty Images)

Earlier, he had visited a Duchy of Cornwall housing project at Nansledan in Newquay aimed at giving a home to the homeless. The scheme – in partnership with the Cornish charity St Petrocs – will see 24 homes built on Duchy land for people experiencing homelessness.

In addition to having somewhere to live, the project will provide wrap-around support, and is inspired by Homewards – a five-year programme led by The Royal Foundation of The Prince and Princess of Wales to show that it is possible to end homelessness. Construction is set to begin in September and the first homes are due for completion in the autumn of next year.