We may not have much meaningful film of Britain’s Queen Victoria, who died in 1901, but Daisy Goodwin says she left an equally revealing imprint: a lifetime of handwritten letters.

Those letters are the primary foundation Goodwin used to write Victoria, the PBS series that launches Sunday at 9 p.m. ET (check local listings).

“She wrote thousands of letters,” says Goodwin. “When you read them, you get a real sense of her voice. I felt like I knew who she was.

“They’re expressive and passionate. They’re filled with underlining and capital letters. They’re the dramas of a teenage girl.”

In fact, Victoria got into the habit of letter writing when she was a teenage girl. Her ambitious mother, the Duchess of Kent, kept her in a virtual bubble through those years and among other consequences, Victoria didn’t have all that much else to do.

She remained a prolific correspondent for the rest of her life, and was candid in her assessment of the people and situations around her.

The cumulative effect of the letters, says Goodwin, was multifold.

First, she says, they absolutely debunk the “myth” that Victoria was cold and distant. “She was passionate about many things,” says Goodwin. “You can’t read the letters and come to any other conclusion.”

Jenna Coleman, who plays Victoria in the PBS series, says that passion helped her survive her first years on the throne, when many powerful forces wanted her either removed or demoted to a figurehead whose decisions were made by others in a regency.

“She was naïve in some ways,” says Coleman. “When you’re young, sometimes you don’t challenge older people. She had never held real power before and once she did, she had to learn how to handle it.

“And remember, she was a teenager. When I was 18, I was preparing for drama school, not for being queen of England.”

Goodwin says there’s a yin-and-yang difference between Victoria’s ascent to the throne and that of Queen Elizabeth II more than a century later.

Elizabeth had been groomed for the position all her life. She learned the requirements, the protocol, the manners. She watched it all first-hand, so in a sense she just graduated into the job for which she had been studying.

“It was so different for Victoria,” says Goodwin. “Not only did she not have that schooling, but she had never had a chance to develop a public face. She didn’t know the politics of the position, and how you must work not to offend people or be seen as too partisan.

“If she thought something, she said it, as she did in her letters.”

“So much of what she wrote is effusive and romantic, says Coleman. “Because she wrote so much, we’ve got such detail to work with. We know about her daily life. Our only problem [with the series] was that we had to get through it so quickly. Daisy Goodwin had to write a book to get in the things we didn’t have room for.”

In an unusual twist, Goodwin’s book, also titled Victoria, was written after she completed the script for the TV series.

“I’d always been fascinated by British royalty,” says Goodwin. “When I went to university and started reading her letters, Victoria became my special subject. By the time I was 19, I was writing about her and I suppose becoming something of an expert.

“Writing a series wasn’t that much of a stretch, because she spoke to me. I just wanted the story to feel real and I wanted her to feel like a teenage girl – a spirited young woman much as we see spirited young women today.

“Like a Taylor Swift.”

“She was brought up in a sheltered environment, but she still had an awareness of the world around her,” says Coleman. “When she was young, they lived near a family of gypsies, and she saw how their lives were different.”

However all the elements came together, Goodwin says. Victoria’s is a story worth admiring and celebrating.

“Here’s a teenage girl facing all these odds,” she says, “and growing up to become the most popular person in the world.”