Excerpts from a New York Times interview (Feb 24, 2020):

“Hilary has reset the historical patterns through the way in which she’s reimagined the man,” said Diarmaid MacCulloch, an Oxford theology professor who published a new Cromwell biography in 2018. “It’s fiction which is extraordinarily probable, and it’s remarkably like the Cromwell I’d been excavating myself.”
Hilary Mantel has a recurring anxiety dream that takes place in a library. She finds a book with some scrap of historical information she’s been seeking, but when she tries to read it, the words disintegrate before her eyes.
“And then when you wake up,” she said, “you’ve got the rhythm of a sentence in your head, but you don’t know what the sentence was.”
To an unusual degree for a novelist, Mantel feels bound by facts. That approach has made her latest project — a nearly 1,800-page trilogy about the 16th-century lawyer and fixer Thomas Cromwell — more complicated than anything she’s undertaken in her four decades of writing.