There’s a reason you haven’t heard much about The Crown’s third season yet: creator Peter Morgan is busy re-casting the beloved period drama, in order to fast-forward the action to about 1970, when its central British royals are a bit older and, possibly, wiser. So far, The Crown has confirmed only its main Season 3 star: Olivia Colman, who will replace Claire Foy as Queen Elizabeth. (Helena Bonham Carter has reportedly signed on to succeed Vanessa Kirby as Princess Margaret, while Paul Bettany has bowed out of discussions to play Prince Philip.)

In a conversation with Vanity Fair last week, Crown casting director Nina Gold explained why casting the period drama this time around is especially challenging.

“Not only are we casting real-life characters,” explained Gold, who has also cast Game of Thrones, “but as we get closer to the present day, many of these people are very much alive. So we have to honor them by picking the right actor to play them—while making a link between the actors who played these characters in the first seasons.”

When Gold and Morgan cast Colman, for example, they saw in her the same uncanny quality Foy brought to her portrayal of the monarch: the ability to simultaneously convey a stoicism and emotional transparency. “They allow you to somehow see into them without really doing anything,” explained Gold. “They each have such easy access to their humanity.”

For a character such as Queen Elizabeth—whose primary function is to appear strong and steady in the face of change—this ability to wordlessly express complex inner emotions is crucial. (Both actresses’ large, expressive eyes help too.) “You can really witness their own internal battle to be and to do good,” said Gold.

The third season will also bring a new generation of matured royals into the feature fold—including Prince Charles, Princess Anne, and Camilla Shand (later known as Camilla Parker Bowles). Gold, who is currently casting these characters, said that the actors she taps for those parts will likely be up-and-comers.

“We’re unlikely to cast a major movie star,” said Gold. “It’s quite interesting and fun to try and find new or new-ish talent. When we cast Claire and Vanessa, they had done loads of really good work, but they weren’t very well-known to this kind of worldwide audience—which was great, because they totally owned the characters without too much baggage.”

“Charles, Camilla, and Anne are going to be pretty interesting characters to follow, because they are just coming into their own,” said Gold. “We’ve cast a pretty wide net for these new young characters.”

Ahead, a few clues that Gold offered about casting these key roles—as well as her two cents on the potential of a Diana Spencer cameo late in the season.

Prince Charles

Given the nature of the series—which has covered about seven years each season—the actor cast as Charles could potentially be playing the prince for about 14 years of the character’s life. This time span—plus the occasional flashbacks Morgan scripts in—means that Gold is auditioning actors across a much larger age range than usual.

“We’re looking for a quite wide age range, which is quite challenging. I think we’re going from 1964 when we start . . . and then we have to get him to about 16 to the late twenties. There are a lot of changes in any young man’s life at that spread of ages. But I think ultimately, it’s not really about the numbers on somebody’s birth certificate as it is how they feel, and how far each individual can stretch their age range, which is really variable from person to person.”