He writes: “Observers also noted that Harry’s face was ‘quite tense and unsmiling’ – and that when William sat down close to him, he barely greeted his brother. Throughout the service, Meghan megawatted away with her best TV smile but, as the ceremony progressed, Harry appeared to grow gloomier. According to one observer, ‘his accelerated blinking even suggested he might have been fighting back tears.'”

Harry later told how he felt at the service in his and Meghan’s controversial Netflix series released at the end of 2022. The service was the first time he and Meghan had seen many family members since an extended Christmas stay in Canada – and the news broke about them quitting the Firm.

Harry explained: “The first time that we saw the other members of the family was in Westminster Abbey. We were nervous seeing the family because all the TV cameras and everybody watching at home and everybody watching in the audience.

It’s like living through a soap opera where everybody else views you as entertainment. I felt really distant from the rest of my family, which was interesting because so much of how they operate is about what it looks like, rather than what it feels like. And it looked cold. But it also felt cold.”

At this year’s annual service on Monday, it will draw on the theme of resilience – at a time when the royal family has faced a barrage of health troubles. But the service will focus on stories of environmental resilience and marine sustainability, through performances representing the five regions of the Commonwealth.

A pre-recorded video message from Head of the Commonwealth, Charles, who is undergoing treatment for cancer, will be played during the service, Buckingham Palace said. Camilla will carry out a second engagement afterwards when she attends the annual Commonwealth Day Reception at Marlborough House in London, meeting foreign ministers, UK parliamentarians and High Commissioners.