Olivia Williams to play Camilla Parker Bowles on 'The Crown'

Camilla, Duchess of Cornwall opens Royal National Hospital for Rheumatic Diseases (RNHRD) and Brownsword Therapies Centre on October 22, 2019 in Bath, England. Photo / Getty Images

Olivia Williams will play Camilla Parker Bowles on "The Crown".

The "Nevers" actress will take over the role of the future Duchess of Cornwall from Emerald Fennell in the upcoming fifth season of Netflix's regal drama, which will cover the most volatile period of her relationship with Prince Charles; before and after the death of Princess Diana.

According to the Daily Mail newspaper columnist Baz Bamigboye, Williams underwent a "chemistry test" with Dominic West, who is set to play Charles, to see if they were compatible on screen together before she was offered the role.

As well as West taking on Charles - who was played by Josh O'Connor in the past two seasons of the show - the cast refresh for the next season of the drama will see Imelda Staunton taking over as Queen Elizabeth from Olivia Colman and Tobias Menzies handing over Prince Philip to another former "Game of Thrones" star, Jonathan Pryce.

Lesley Manville will replace Helena Bonham Carter as Princess Margaret and "Tenet" actress Elizabeth Debicki will play Princess Diana in the latter part of her life, taking over the role from Emma Corrin.

It was previously reported producers were hoping to land "Fleabag" star Andrew Scott to play Prime Minister of the time Tony Blair, but he would need to rearrange other commitments in order to be available for filming.

English actress Olivia Williams during production of the TV film adaptation of Jane Austen's "Emma", circa 1996. Photo / Getty Images

Charles and Diana's youngest son, Prince Harry, recently admitted he'd watched the show and though it isn't "strictly accurate", he felt it gave viewers a "rough idea" about royal life.

He said: "It's fictional, but it's loosely based on the truth. Of course it's not strictly accurate; it gives you a rough idea about what that lifestyle is, the pressures of putting duty and service above family and everything else, what can come from that.

"I'm way more comfortable with 'The Crown' than I am seeing the stories written about my family, my wife, or myself.

"That is obviously fiction, take it how you will, but this is being reported on as fact because you are supposedly news. I have a real issue with that."