The Crown's creator Peter Morgan has said it is unlikely Claire Foy and Matt Smith will appear in future seasons as time progresses in the programme.
The hit Netflix series follows the story of Queen Elizabeth II and Prince Philip, with the first season having focused on the years between 1947 and 1955.
The second series will then focus on the years of the monarch’s life from 1956 until 1963, through to the retirement of the Queen’s third prime minister Harold Macmillan.
But, as the subjects of the lavish programme age, it seems unlikely that Claire and Matt will be able to continue to portray the Queen and Prince Philip.
The Crown’s writer and creator Peter told ScreenDaily that show bosses are “having conversations about whether to go forward” with the third series.
He added: “If we do … we’d probably need to think about the issue of recasting everybody and so those conversations are happening now and I couldn’t tell you where we’ll come out.
“It’s a big thing to go on again. Everybody needs to look at one another and say ‘what is the appetite (for this)?’ and under which circumstances and what terms would we do it.”
He said that the years of 1963 and 1964 – in which the Queen was 37-38 – may be the furthest Claire, 32, can go without having to resort to “silly” make-up to look older.
Peter said: “I feel that when we reach 1963-64 we’ve gone as far as we can go with Claire Foy without having to do silly things in terms of make-up to make her look older.
“She can’t help the fact she’s as young as she is…”