"If anywhere else had magic, then they were doing a damn good job of hiding it." Strange knew that nobody in Europe had magic, otherwise they'd have used it in the peninsula. But places like Africa, Asia...he hadn't heard of anybody having magic there but, then again, that doesn't mean it didn't exist.

"As for how long ago it was brought back..." There's a pause, while Strange does some quick sums. "Less than ten years ago, I'd imagine? Though really, I've no idea how long Norrell was practicing before he decided to go public with his magic--come to think of it, I've no idea how long Childermass was practicing either."

It seems Strange has succeeded in confusing himself more than he's succeeded at giving Syrlya an actual answer.