Nikolaj Coster-Waldau) are set to executive-produce and star in the new period drama, playing 11th century figures William, Duke of Normandy, and Harold, Earl of Wessex, respectively.

Source: https://tvline.com/news/nikolaj-coster-waldau-king-and-conqueror-bbc-cast-1235089919/

Prince Edward will remain Earl of Forfar - a title conferred by the Queen on his 55th birthday in addition to his Earl of Wessex title, given on the day of his 1999 wedding.

Source: https://www.9news.com.au/world/royals-uk-has-new-duke-of-edinburgh-as-king-charles-gives-his-brother-prince-edward-title/9ca07207-c387-419c-8c39-e00a591faf16

The Earl of Wessex and Princess Royal are expected to take part as Prince Charles' siblings.

Source: https://www.dailymail.co.uk/femail/article-11663403/King-Charles-Queen-Consort-Camilla-head-Sunday-church-service-Sandringham.html?ns_mchannel=rss&ns_campaign=1490&ito=1490