Let it be known that Lady Fiona Herbert, the eighth Countess of Carnarvon, occasionally answers her own phone. When I call the Countess’s office to discuss her new book, Lady Almina and the Real Downton Abbey, I am unusually anxious; it’s not every day I speak to a member of the British aristocracy. “Hello?” answers a startled-sounding voice. I nervously ask if Lady Carnarvon is available. “This is Lady Carnarvon,” the voice replies, erupting into hearty laughter—which, happily, is not directed at me. The Countess had been reaching for the phone just as it rang and was caught off guard. “I’m completely useless as a receptionist,” she says.

For a woman who lives at Highclere Castle, one of Britain’s most impressive “family piles,” as well as the primary setting of the spectacularly popular PBS costume drama Downton Abbey, Lady Carnarvon is surprisingly warm and unpretentious.

She projects an image of slightly disheveled glamour: her household is not a well-oiled machine, but something more akin to a living archaeological site, where one might just discover a decades-old scrapbook while foraging through an out-of-use desk drawer. “We found a staircase recently. That was quite exciting,” she tells me.

Downton Abbey isn’t Highclere’s first brush with fame—parts of Eyes Wide Shut were filmed there, and British tabloid curiosity Jordan celebrated her 2005 wedding at the castle, arriving via a pumpkin-shaped carriage—but the phenomenal success of the series has thrust the Carnarvon family’s ancestral home into the spotlight like never before. It’s also spawned a cottage industry of Downton Abbey tie-in books, including two competing biographies about Almina, the colorful and controversial fifth Countess of Carnarvon.

Widely believed to be the illegitimate daughter of industrialist Alfred de Rothschild and his French mistress, Marie Wombwell, Almina married George Herbert, the fifth Earl of Carnarvon, in 1895, when she was just nineteen. In Lady Carnarvon’s telling, it was a felicitous match romantically and financially. Dubbed “the Pocket Venus,” diminutive Almina was a renowned beauty, reportedly besotted with her new husband, a budding Egyptologist. More important, perhaps, Almina brought to her marriage the cash desperately needed to run Highclere. Lady Carnarvon’s book focuses on the tumultuous years of World War I, when Almina converted her palatial estate into a convalescent hospital for wounded officers, and ends rather abruptly in 1924, shortly after the Earl’s untimely death.

Downton Abbey fans will note the striking parallels between Almina’s life and that of her fictional counterpart, Lady Cora Crawley. This is hardly an accident: Lady Carnarvon and her husband, the eighth Earl of Carnarvon, affectionately known as Geordie, have been friends with Downton Abbey creator Julian Fellowes for more than a decade. Though Lady Carnarvon calls Fellowes a “genius,” she’s too involved with the show to call herself a fan. “It’s too much of a bloody muddle,” she says.

Yet Lady Almina portrays a lifestyle far more extravagant—and a hierarchy far more rigid—than anything on Downton Abbey. In one of the book’s most evocative passages, Lady Carnarvon describes how Almina spent the equivalent of £360,000 on a three-day visit by the prince of Wales, the future King Edward VII. On his first night at Highclere, the prince, a notorious glutton, enjoyed an impossibly decadent meal:

It began with a soup, a consommé, followed by the fish course: turbot grillé Dugléré, (after Adolphe Dugléré, who was one of the most famous chefs in nineteenth-century Paris and had cooked for the Rothschild family for years.) Then came the entrées: pâtés and a chicken dish. Next up were the roasts, a vast amount of game birds, stuffed with foie gras, all served with numerous vegetable side dishes. It was followed by a soufflé d’orange and ices. After the entertainments (on this occasion, accounts show that a band played for the assembled guests in the Music Room), there was a light supper of cold meats such as pheasant and cold beef.

Later chapters about the war years at Highclere, while less exuberant, are full of sumptuous details, such as the “cheerful crushed-strawberry-pink” uniforms Almina designed for her team of pretty Irish nurses, or the soft down pillows and fine sheets on each patient’s bed.

In Lady Almina, Lady Carnarvon portrays her predecessor as a woman with a vast charitable streak and a knack for getting what she wanted—particularly from her “godfather,” Alfred, who footed the enormous bill for her war-time hospital. “She spent money like water, but she spent it saving lives. If you’re going to distribute your fortune, that’s a pretty good place to start.

Though the book is explicitly aimed at fans of Downton Abbey, reading it doesn’t feel quite as silly as it perhaps ought to. With or without the series, the Carnarvon family is intriguing and eccentric in a way that seemingly only wealthy British aristocrats can be. Almina’s husband would discover the tomb of Tutankhamun, dying shortly thereafter of a mysterious blood infection popularly attributed to the “Pharoah’s curse.” An even more fascinating character is the Earl’s half-brother, Aubrey Herbert, who was close friends with T. E. Lawrence and was twice offered the throne of Albania. His daughter, Laura, would become Evelyn Waugh’s second wife (his first wife was Laura’s cousin, also named Evelyn).

Though Lady Almina is little more than a frothy, well-executed piece of Highclere marketing, it is not, it turns out, an entirely uncontroversial book, nor is it the first Almina biography to hit the market. Historian William Cross beat Lady Carnarvon to the punch by a few months with his self-published The Life and Secrets of Almina Carnarvon.

A few weeks ago, I called Cross at his home in South Wales to discuss the considerable discrepancies between his book and Lady Carnarvon’s. He was gracious and curiously charming, but it was difficult to get a word in edgewise; over the course of our nearly ninety-minute conversation, I asked him perhaps a half-dozen questions. Cross takes issue with Lady Carnarvon’s decision to end Almina’s story in 1924, shortly after her first husband’s death and her hasty remarriage, barely eight months later, to Colonel Ian Dennistoun. In the very last paragraph of the book, Lady Carnarvon tosses in a pointedly brief mention of a “damaging court case brought by Ian’s ex-wife, Dorothy,” a case that was, in fact, a massive and very expensive sex scandal revolving around her new husband. When Colonel Dennistoun’s ex-wife, Dorothy, learned that he’d remarried a wealthy widow, she sued for alimony. In court, Dorothy further alleged that her ex-husband had forced her to sleep with a high-ranking military officer in order to secure a promotion. Because of Lord Carnarvon’s fame, the scandal was front-page news in the U.K.

The fifth Countess would live for another forty-five years, eventually dying in 1969, at ninety-three, after choking on a chicken bone. Having long since squandered her inheritance from Alfred, the former chatelaine of magnificent Highclere Castle was living in a modest row home in Bristol. None of this depressing business is covered in Lady Almina. “I stopped it in 1924 because that to me was a beginning and an end that I could manage,” the Countess says of her decision to omit Almina’s checkered post-Highclere life.

In his book Cross makes a slew of sensational allegations, some more plausible than others. According to the author, Alfred de Rothschild was not Almina’s real father, but he encouraged the illusion as a way of deflecting attention from his homosexuality. (For her part, Lady Carnarvon never conclusively states that Rothschild was Almina’s father.) To make ends meet in her later years, Cross says Almina provided costly but illegal abortions to upper-class women at Alfred House, the London hospital she opened in the late 1920s. (Evelyn Waugh reportedly called it “Almina’s abortionist parlor.”) His version of Almina is an inveterate maneater, a woman who seduced her second husband’s undertaker and later took up with a decades-younger working-class lover named James Stocking.

Not surprisingly, the ever-judicious British press has latched on to Cross’s allegations, especially his outlandish claim that Almina’s son, the sixth Earl of Carnarvon, was in fact sired by Prince Victor Duleep Singh—the fifth Earl’s best friend and a frequent guest at Highclere. The incomparable Daily Mail even contacted the “real Earl of Carnarvon,” a Devon school teacher named Alan Herbert, to tell him that he has “a strong claim” to the title. (His reported response: “Wow.”)

Cross himself is not exactly diplomatic. He accuses Lady Carnarvon of writing a “hugely diluted and sanitized” version of Almina’s life and sees her hagiography as part of a broader conspiracy to consolidate power among the landed class. “Britain is still absolutely under the control of the aristocracy,” he says. “That, in 2011, isn’t right.”

Cross is even less restrained online, where he’s posted scathing reviews of Lady Almina on Amazon. “Know that toffs will not be transparent,” Cross warns the would-be reader, describing the fans who “follow this TV series as mesmerised as grazing sheep watching car headlamps flicking in the winter darkness of night.” He likens Lady Carnarvon’s book to Orson Welles’s famous “War of The Worlds” broadcast and, yes, to Nazi propaganda: “It seems a case of employing the technique of Mr. Goebbels that if one utters a big enough untruth and keep repeating it, people will eventually come to believe it.”

So what does Cross think of Downton Abbey? “Oh, I enjoy it very much,” he tells me. “I think the story lines are fantastic.”

Meredith Blake is a freelance writer living in New York. She is a frequent contributor to The A.V. Club and The Los Angeles Times.