The English nobility of the early 20th-century Downton Abbey had plenty of hired help to keep up appearances. A century later, however, the estate must operate like a modern business, the countess of Highclere Castle told CNBC on Wednesday.
"We exist today because we end up working quite hard," said Lady Fiona Carnarvon on "Squawk on the Street." "And like any other business, it's a diversification."
Running an English estate comes more easily when you descend from the Carnarvon that discovered King Tutankhamun's tomb. The countess said a "tremendous sale" at Christie's in 1926 left the family better positioned to handle the upkeep of Highclere, which is the Carnarvon family seat and the setting for the Masterpiece series on PBS, "Downton Abbey."
Marketing off the wildly popular show, the Carnarvons hold weddings, tours, private dinners and other period events at the home. ("Downton Abbey," now in its fourth season, tells the story of a family of nobles and their servants in World War I-era England.)
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Though Carnarvon would not disclose the cost of getting married at Highclere, it's reasonable to assume that celebrants pay a premium to party among priceless works of Dutch Old Masters and Egyptian artifacts.
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"Oh, I don't talk about money, because I'm a countess," she said, laughing. "I am an accountant. But I like net margins. That's much more interesting than sales."
The family live in a side house in summer, when the main estate is open for tours. Much of the massive house remains frozen in time. The castle doesn't have elevators or showers, Carnarvon said. Only one of its hundreds of rooms contains a television.
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"We've got a wonderful selection of works of art collected over hundreds of years," she said. "In the cellars, we've actually got an Egyptian exhibition as well. … We have lots of different events to try and draw people in. There's a culture. We want to try and make people love it. … Fortunately for us, 'Downton Abbey' has really done that."
—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street."