Their escape ride was also with them. Harry, Hermione learned, had been secretly learning how to ride a motorcycle with Sirius before the man’s death. Apparently, it came as easily to him as flying a broomstick. While he never got to ride it, the bike having been stolen by Gringotts, it gave him a skill they would need once it was time to escape. The alley wasn’t ideal for this as, while it was warded against muggles, everyone would be able to see them vanish inside it, breaking the Statute. So, instead, Harry stole a racing bike from somewhere on the street. A simple Alohomora could turn it on. The bike, which they would use to escape, was parked on the side of the street, ready for them to drive away on.