The third season of The Crown is looking at "established actors" to play opposite Olivia Colman as the new Prince Philip.

Speaking last night at a BAFTA Masterclass, showrunner Peter Morgan revealed that casting is still ongoing on the third and fourth seasons of the Netflix drama.

"We're doing them back-to-back," Morgan said. "The third season... I can tell you that it starts in 1964 and that it ends in 1976, and that I've written some of the episodes. We've got Olivia, which is fantastic, and now we're just embarking on the process of casting."

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Colman, he revealed, accepted the task of replacing Claire Foy as the Queen "on the spot" – which means the team behind The Crown are now "slightly catching up" when it comes to casting the other major roles.

"Normally it's a big old palaver – you talk to the agent, you talk to this person," Morgan explained. "But this was all very quick."

Colman's casting as the new Elizabeth II was announced in October last year, with Morgan suggesting the Broadchurch actress has an "ability to be both plain and dazzling, and to be both knowable and unknowable".

"There's a sort of everywoman [quality]," he suggested. "There's something very connectable, and yet quite anonymous about Olivia. Now we've spent some time with her and it's exciting. But we've just started the [casting] process."

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Morgan did reveal, however, that some "pretty established actors" are being considered to replace Matt Smith as Prince Philip. (Paul Bettany was briefly thought to be the frame, though later dropped out.)

Philip's background, which was explored in the second season, will continue to be a focus of future seasons, he also confirmed.

Helena Bonham Carter is also thought to be in line to replace Vanessa Kirby as Princess Margaret as part of a total cast overhaul. "It's hard to recast," said The Crown's executive producer Suzanne Mackie. "But once you've made that commitment, it's all or nothing. Everyone has to change."

The changes might not just be in the casting, either, with Morgan admitting he is approaching the writing of the third and fourth seasons differently. "These scripts [for the first two seasons] were all about 50-60 pages, and I think they were sometimes too busy and I think that they sometimes had too much going on, they were too indigestible.

"I'd like to strip them down [in future]. It shouldn't all just be yadda yadda yadda."

The Crown streams exclusively on Netflix.

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