Britain’s Princess of Wales made a return to public life in the midst of her cancer treatment and joined other members of the British royal family to celebrate King Charles’s official birthday.

Kate and her three children, Prince George, Princess Charlotte and Prince Louis, were cheered by crowds in central London as they left Buckingham Palace in a carriage procession for the Trooping the Colour ceremony.

After spending much of the year coming to terms with the diagnosis and receiving ongoing chemotherapy, the future queen looked relaxed as she travelled along The Mall, one of London’s most famous thoroughfares, with her family in the glass state coach.

Her appearance was in doubt after she missed the final rehearsal last weekend, but with Charles also suffering from cancer, the spectacle of military pomp and pageantry became a symbolic statement by the British monarchy after a period of uncertainty.

She was surrounded by other members of the family, with her husband, Prince William, on horseback, as were Princess Anne and Prince Edward.

Charles also rode in a carriage with his wife Camilla, a departure from last year because of his illness, and he will inspect the officers and guardsmen from the coach rather than from a horse.

Kate said in a statement on Friday she was making “good progress” with her treatment, but candidly said she has “good days and bad days” and although she has been working from home, said “I am not out of the woods yet”.