Prince Louis helped put a spring in King Charles’s step this week thanks to a sweet gift from the young royal. The King returned to public-facing duties on Tuesday (April 30), visiting University College Hospital Macmillan Cancer Centre where he spoke of his shock at being diagnosed with the disease.

Charles, 75, quietly told royal fans gathered to greet the monarch that he was wearing a T-rex themed tie believed to have been a gift from Louis, aged six, who reportedly likes dinosaurs.

Royal expert Robert Hardman told MailOnline: “His tie said it all. It has been a favourite since he became King, appearing on away days, at Palace receptions and even a trip to church.

“Featuring a blue dinosaur pattern on a pink silk background, it is a cheeky play on his official ‘Charles III Rex’ cypher. Staff know that when ‘C-Rex’ is wearing his ‘T-Rex’ tie, he probably has a spring in his step.”

Charles candidly described the experience of being told he had the disease during the visit in central London to learn about the latest treatments and chat to staff providing the pioneering care.

He also reassured those who asked about the state of his health, saying: “I’m well.”

King Charles wears Prince Louis’ T-Rex tie (Image: Getty)

King Charles was joined by Queen Camilla for his first public engagement since his cancer diagnosis (Image: Getty)

Looking relaxed and in good spirits, Charles was joined on the visit by Queen Camilla. The royal couple went on impromptu walkabouts and met staff who had stopped to catch a glimpse of the King and Queen.

The King enjoyed a warm embrace from his niece, Zara Tindall, when he braved the rain at the Royal Windsor Horse Show in his third public visit of the week.

A popular equestrian attraction, Royal Windsor Horse Show was a firm favourite with his late mother Queen Elizabeth II.

Meanwhile, on Saturday (May 4) it emerged that Charles is to become patron of the Royal British Legion (RBL) after a major review of more than a thousand royal patronages after the death of Queen Elizabeth II.

Charles will become the figurehead of the country’s leading Armed Forces charity as it prepares to mark the 80th anniversary of the Second World War D-Day landings in the UK and Normandy, on June 6.

The review by the Royal Household was carried out with the close involvement of members of the Royal Family and focused on organisations the late Queen supported as patron and those Charles and Camilla represented as patron or president before they became King and Queen.

Prince Louis’ T-Rex tie gift puts a spring in King Charles’s step (Image: Getty)

Zara Tindall and King Charles share a warm embrace at the Royal Windsor Horse Show

Mark Atkinson, RBL Director General, said: “The Royal British Legion is extremely proud that his majesty the King is our new patron. As the nation’s largest military charity, this patronage honours the special relationship that exists between the monarch and the armed forces.

“His majesty’s commitment to remembrance and lifelong support to the RBL’s welfare work is greatly appreciated by our entire community.”

Charles and Camilla will now be joint patrons of the Jockey Club, succeeding the late Queen who was patron of the organisation responsible for a string of high profile racecourses across the UK.

The King retains his patronage of the Samaritans, a role he has held for more than 25 years. Camilla will succeed Queen Elizabeth II and take on the presidency of the Sandringham branch of the Women’s Institute (WI).