Inside Buckingham Palace, the mood was less formal reception and more elegant celebration, as guests gathered to honour Queen Elizabeth.

Champagne flowed alongside a specially created “QEII tribute” cocktail, a non-alcoholic nod to the late Queen’s well-known preference for Dubonnet, reimagined with lemon, rosemary and tonic.

Amid the celebrations, King Charles offered a glimpse into the future, sharing his enthusiasm for the planned national memorial dedicated to his mother.

Reviewing the final designs, he highlighted the placement of a bronze statue by sculptor Martin Jennings along The Mall, set just ahead of a tribute to Prince Philip.

A proposed bridge inspired by the Queen Mary Fringe Tiara, the diamond piece famously worn by the late Queen on her wedding day.

The design will feature a glass balustrade intended to glow softly over the lake in St James’s Park.

The King, joined by Queen Camilla, led a rendition of “Happy Birthday” for three guests also celebrating their 100th year, presenting them with commemorative cards and sharing a cake among around 190 attendees.