"I'd hoped he'd gotten clean after last summer." Charlie closed his eyes for a long moment, and when he opened them, realised that he had apparently made the decision to trust Matt. "Okay, that does help. It helps me pin some things down."
He thought about the timeline again.
"Are you sure it was in April, when you moved into Grimmauld, that he stopped the drugs? And not after he disappeared for a while at the end of February, early March?"