Dominic West's son Senan made his TV debut in The Crown's fifth season, in which he portrayed a young Prince William.
The young actor appeared in three episodes before handing the baton to Rufus Kampa, who plays a teenage version of the now-Prince of Wales in the latest series.
So why didn't Senan act alongside his dad in the final season?
During an interview with the Radio Times, Dominic revealed that he decided his son wouldn't continue on the show due to a sensitive scene in the sixth season.
"I didn't really fancy doing the scene at Balmoral, telling a boy his mother has died," the actor explained.
"They invited Senan back because he did such a good job, and he was great, but I did slightly baulk at that. It was unfair of me, because he did want to do it, but I wouldn't have fancied that, to be honest."
In season six part two, actor Ed McVey takes on the role of Prince William as he meets Kate Middleton (Meg Bellamy) whilst studying at St Andrews University.
Speaking about playing the royal during an interview on ITV's This Morning, Ed revealed how not having extensive knowledge on William's younger years helped his portrayal. "I wasn't alive when Diana passed but I think it was kind of helpful not having an intrinsic knowledge and understanding or a passionate feeling towards the characters at that time so you're able to just look at the characters on the page and figure it out," he said.
Chatting about how he got into character, Ed added that he used a vocal technique and would say a particular sentence to help him find William's voice. "With the voice, I had a sentence which was, 'Around the roundabout and down to Chile to play polo,'" explained the actor.
The new episodes see Prince William return to Eton as he's still coming to terms with the death of his mother whilst dealing with an increase in attention from young female fans.
In later episodes, he enrolls in St Andrews University, where he meets Kate Middleton.
The official synopsis teases: "Later, as Prince William takes up his place at St Andrew's University, the omnipresent conflict of life as a public servant continues as he tries to balance the traditional undergraduate rites of passage with the constraints of his position and constant presence of personal protection officers."
Elsewhere, the Queen reflects on her reign and legacy following her Golden Jubilee, as well as the passing of her mother and sister.
The synopsis reads: "With the passing of her sister and her mother, her Golden Jubilee and having approved the marriage between Prince Charles and Camilla, the Queen starts to consider her reign and ultimately her legacy. Approaching her ninth decade, the Queen is forced to dig deep and really examine what is best for the future of the monarchy."
All seasons of The Crown are available on Netflix.