Laura Windsor, who is the UK’s Queen of Etiquette, explains that for such royal occasions being modest is key.

As reported by the Mail, she said: "Shoulders should always be covered, and the golden rule of dressing is to adhere to protocol. Protocol is there for a reason as every time it is breached, a member of the Royal Family becomes headline news.

"Meghan was a member of the Royal Family and should have respected protocol. By breaching protocol, she was sending a pretty clear message. In my view, that made her a poor decision-maker."

She then suggested that Meghan likely thought that she could overturn such traditions, adding, "I would expect an emotionally mature person to respect the tradition and protocol of a country. Meghan chose to take her own independent path with her fashion choices."

Also speaking of Meghan's choice of outfit for the event, royal expert Myka Meier of Beaumont Etiquette added: "The bottom line is that the outfit always has to fit the occasion.

"It has to be modest, elegant and appropriate, and it should never distract from the role."

Meghan also attended Trooping the Colour in 2019. The Duke and Duchess of Sussex made the decision to step down from royal duties in early 2020 - meaning they haven't attended the event since.