He's there to take your photo and thinks that you're there to take his card. As soon as he snaps a pic of your crew, he's exploiting your momentary blindness from the camera flash to stuff his contact info into your hand. And then he reminds you of his website and gives you a pound every time you see him the rest of the night. The struggle is that real, people.
And then of course while you write him off for the evening, he'll pull some model from underneath your nose because he promises her free test shots. It's also entirely possible that this dude caught some photographic evidence that can be used to blackmail you, so be wary of this one. He is, after all, the most sober dude at the party. Except for the guy who believes in Mormon chic.