The BBC has been adapting the novels of Charles Dickens for as long as it’s been doing drama. What’s new is the depth and breadth — OK, the length — of the latest TV versions, the most recent being “Little Dorrit.”

“Before, we were doing Dickens in shorter bursts,” says Kate Harwood, the Beeb’s head of series and serials, drawing a contrast between previous efforts and the work of Andrew Davies, who penned “Little Dorrit” and the much-honored “Bleak House” (2005), both co-productions with WGBH Boston.

“Dickens works better on telly than on film, because these stories need time,” says Harwood, justifying “Little Dorrit’s” seven hours. “‘Come back next week,’ you know. It really benefits from that.”

As for why “Little Dorrit” and why now, Harwood offers two reasons: The novel hadn’t been adapted in 21 years, and Davies was keen on it. “Andrew likes writing for strong woman characters,” Harwood says. “And he recognized a challenge in Amy Dorrit. She’s so obliging in the book that we used to call her Little Doormat. But he makes her fresh and truthful and slightly less pained. And Claire Foy, who plays her, is wonderfully repressed. She’s a lovely find.”

Amy Dorrit is just one of 79 roles in the mini. “It was the most massive casting exercise,” Harwood says. But getting actors to sign on proved easy: “You can ask almost anyone to do them, because even the small parts are such performance opportunities — catnip to actors. In fact, you have to beat them off with sticks.”

In light of the reception “Little Dorrit” has received, you might expect a raft of Dickens coming, but it seems audiences will have to wait. “We’re giving him a couple years off,” Harwood says. “But it’s his bicentenary in 2012, and it’s fair to say there are several more coming.”