So where does the on-screen friendship between Queen Elizabeth and late Reverend Billy Graham fall?
In the sixth episode of the second season, Elizabeth watches one of Billy's sermons on television alongside the Queen Mother.
She's absolutely transfixed by Billy, later telling Prince Philip that she thinks the young evangelist is "quite handsome."
Then she invites Billy for a sermon at Windsor Chapel and a lunch in her royal company, and she tells him she wants to be a "simple Christian." Turns out, Elizabeth and Billy were indeed quite close in real life, according to People. He'd visit her when he was in the UK, and she'd visit him when she was in the US.
"No one in Britain has been more cordial toward us than Her Majesty Queen Elizabeth II," the preacher — who passed away from natural causes at age 99 on Wednesday, Feb. 21 — wrote in his 1997 autobiography, Just As I Am.
"Almost every occasion I have been with her has been in a warm, informal setting, such as a luncheon or dinner, either alone or with a few family members or other close friends."
Billy said he believed the devoutness of Elizabeth's mother set an example for her, a claim The Crown historical consultant Robert Lacey has corroborated.
"Her Christian faith is fundamental to her in an old-time evangelical way, deriving from the example of her mother, who knelt at her bedside every night to say her prayers. It is said that the Queen does the same," Lacey once told People.
From the sound of it, Queen Elizabeth is quite studied in her religiosity.
"After preaching at Windsor one Sunday, I was sitting next to the Queen at lunch," Billy wrote in his book.
"I told her I had been undecided until the last minute about my choice of sermon and had almost preached on the healing of the crippled man in John 5. Her eyes sparkled and she bubbled over with enthusiasm, as she could do on occasion. 'I wish you had!' she exclaimed. 'That is my favorite story.'"
And speaking of favorite stories, The Crown creator Peter Morgan thinks the Elizabeth-Billy scenes represent "the best bit of writing" in Season 2.
"The Billy Graham episode is about Elizabeth wanting to deepen her Christianity," he told Vanity Fair. "She stops reflecting on forgiveness as a central tenant of Christianity at precisely the time that she's asked whether she can or can't forgive her uncle for [meeting with Nazis and a general inclination toward appeasement]. The two story themes dovetail quite nicely."