Royal resemblances within King Charles's family are often noted, particularly between parents and their children in photographs from the archive.
The similarities between Princess Charlotte and her father, the Prince of Wales, and her late grandmother, Queen Elizabeth II, are often picked up in their childhood photographs.
And in a post shared by the Royal Collection Trust to mark King Charles's first birthday parade, Trooping the Colour back in June, royal watchers couldn't help but notice the similarities between the image of two-year-old Prince Charles, and his youngest son, Prince Harry.
The photograph shows Charles riding in a carriage with his late grandmother, the Queen Mother, and his aunt, the late Princess Margaret, at Trooping the Colour in 1951. His mother, Elizabeth II, had taken the salute on behalf of King George VI who was unwell.
The young prince can be seen seated between his grandmother and his aunt, wearing a double-breasted collared coat with a tartan blanket on his lap.
"Spitting image of Harry," one Instagram user commented. "I thought the same!" a second agreed.
"He looks like Prince Harry," a third added.
And indeed, if you look at images of Harry at around the same age, you can see the strong father-son resemblance.
One photograph shows an 18-month-old Harry wearing a similar-style coat to the one worn by young Charles.
The tot can be seen holding his late mother, Diana, Princess of Wales's hand as the family step off a plane at Aberdeen airport, as they head to Balmoral Castle.
In the coming weeks, King Charles will welcome members of the royal family to Balmoral during his annual summer break.
While the Prince and Princess of Wales and their three children are expected to be among the guests, it's unlikely that the Duke and Duchess of Sussex will fly over from the US.
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Harry has shared details about his complicated relationship with his father, brother and stepmother, Queen Camilla, in the Netflix docuseries released last December and his memoir, Spare, published in January.
Despite their estrangement, the Duke attended King Charles and Queen Camilla's coronation at Westminster Abbey in May. See Harry's arrival at the service with his cousins, Princess Beatrice and Princess Eugenie, in the clip below…
It's not known when Harry will make his next trip to the UK, but he is expected to fly to Dusseldorf for the Invictus Games from 9 to 16 September.