Dame Diana Rigg has signed up to join royal drama Victoria.
The veteran actress will join Jenna Coleman, who reprises her role as the monarch, and Tom Hughes, who is back as Prince Albert, in the second series.
The Avengers and Game Of Thrones star Dame Diana, 78, will play the Duchess of Buccleuch, the young Queen’s new Mistress of the Robes, who is “renowned for speaking her mind”.
Queen Victoria faces the challenge of motherhood in the new ITV series.
Taking place six weeks after the first series ended, the second instalment establishes Victoria “as a working mother, learning to balance her responsibilities as both parent and Queen”.
But with “Prince Albert still struggling to find a role for himself there is an inevitable power struggle between husband and wife”.
The drama’s creator, Daisy Goodwin, said: “Victoria is the only Queen regnant to marry and give birth while on the throne and the challenges of being head of state as well as a wife and mother are legion.
“In many ways, Victoria’s dilemma is a modern one – how do you have a successful marriage and a happy family when you are holding down an important job. Can you really have it all?”
Executive producer Damien Timmer said of the new series: “At the centre of it is a beautifully nuanced study of a young marriage, and it’s a joy to watch Jenna and Tom find new layers to this iconic couple.”
The eight-part series and two-hour Christmas special will feature drama in Buckingham Palace, as well as the couple’s trips to France and Germany and see Victoria and Albert discover sanctuary in the Isle of Wight.
The first series went head-to-head with BBC drama Poldark and was ITV’s highest rating drama of 2016.
And the show’s stars, Jenna and Tom, are said to have become a real-life couple since filming the first instalment.