Three up…two across…” he muttered. “Right, stand back, Harry.”
He tapped the wall three times with the point of his umbrella.
The brick he had touched quivered - it wriggled - in the middle, a small hole appeared - it grew wider and wider - a second later they were facing an archway large enough even for Hagrid, an archway onto a cobbled street that twisted and turned out of sight.
“Welcome,” said Hagrid, “to Diagon Alley.