Los Angeles, Jan 15 (IANS): Actress Helena Bonham-Carter will replace Vanessa Kirby to essay Princess Margaretm in "The Crown".

Kirby announced the news as she posted an Instagram photograph in which she stands side-by-side with Bonham-Carter, with the caption "Honoured", reports variety.com.

Kirby has played the role of the Princess for the first two seasons, but the third season will feature an all-new cast in the major roles.

Olivia Colman has been confirmed to play Queen Elizabeth, taking over the role from Claire Foy. But there has been no announcement yet about who will inherit the role of Prince Philip, played by Matt Smith in the first two instalments.

Series creator Peter Morgan has for a long time intended to replace key cast members in later seasons of the series to better portray the main characters as they age.

"You can't ask someone to act middle-aged," Morgan told Variety ahead of the season one premiere.

"Someone has to bring their own fatigue to it. The feelings we all have as 50-year-olds are different than the feelings we all have as 30-year-olds. That informs everything we do."

Seasons 3 and 4 have not been officially ordered, but early production is said to be underway.