Joan Marcus
November 02, 2015 07:50 AM

For Lydia Wilson, star of Broadway’s King Charles III, suiting up as the well-appointed Princess Kate was quite a daunting task – but it helped to know she and the Duchess of Cambridge are cut from very similar cloth.

When self-professed “worst royal watcher” Wilson, 31, began to research Kate’s biography in preparation for the role, she discovered she had more in common with Kate than she could have imagined – and a family history worthy of Downton Abbey to boot.

Wilson tells PEOPLE in this week’s issue that auditioning to portray England’s future queen – a scheming power player who is much more similar to Lady Macbeth than the serenely poised and gracious Kate – was a surreal experience. She went into read for a role named “Kate,” and recalls that “it quickly dawned on me that this was Kate Middleton.”

Along with playwright Mike Bartlett and director Rupert Goold, Wilson decided to avoid impersonation and embrace a more expressionistic version of the commoner turned princess. “I just sort of made her up as I would have made up a fictional character,” says Wilson, “and it’s been a process of slightly horrific realization that lots and lots of people are watching this and that I have a responsibility.”

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Oliver Chris (as Prince William), Lydia Wilson (as Princess Kate) and Richard Goulding (as Prince Harry) in Broadway's King Charles III
Joan Marcus

Wilson assuaged the weight of that responsibility by connecting to Kate’s backstory.

“I found out there were a lot of similarities. Our backgrounds are very mixed. On my dad’s side, my family used to work as servants in one of the big castles in Yorkshire, and it’s been quite a middle-class story,” she says, revealing that her own relatives have more in common with Carson and Thomas Barrow than with Lord Grantham.

As has been well reported, Kate also came from humble beginnings: her great-grandfather was part of a coal mining family in northern England before he struck out for London – a move that would have effects spanning generations and would ultimately position Kate to meet, marry and start a family with Prince William.

This incredible story and the potential that Kate represents is not lost on Wilson, especially as the play – which envisions the aftermath of Queen Elizabeth II‘s death on her heirs – reaches a surprising climax.

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“There’s this amazing bit at the end if the play where I get to sort of sit on stage and stare out at the audience,” says Wilson.

“I feel like I receive almost unconscious messages from the audience about what this image of ‘Prince’ and ‘Princess’ means. And the thing that’s really vivid is this idea of a fairy tale coming true,” she continues.

“Kate’s story seems unreachable, and yet she is now in that position. To me, the silent voice of the audience is [communicating] how fairy tales can come true and how Kate embodies that possibility.”

Khloamp#233; Kardashian on the cover of PEOPLE

For more on King Charles III, pick up this week’s issue of PEOPLE, on newsstands now

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