Vernon sorts out the care packages to the people he knows well enough to have carried their stuff for them first. Then, more complicatedly, it's the care packages of people he doesn't know, but only the ones that have easy covers like having letters attached, the rest he needs to find more sneakily. While freshmen are generally considered too innocent to mess with, he still doesn't want to loudly proclaim to everyone, 'Hey I have a valuable, easily snatchable thing for someone I don't personally know, come trick me out of it because I don't matter.' He's not stupid. But he'd like to disguise those deliveries with actual letter deliveries, so as not to make it too obvious what he's doing. Fortunately (?) he has some extra letters he didn't have a plan for, dumped on him at 6 AM without any warning. Those will work between package deliveries, none of them matched any care packages at all, he checked. Also, while doing this, keep an eye out for mals, even now, even in this large crowd. It's a good habit to keep up.
"Pevensie?" he calls loudly into the crowd, picking out the letter with the name that is most recognizable. Doesn't know the student, of course, but 'Pevensie' means 'London,' which is very recognizable.