What happened for Winston during the disorder of tearing down posters?

A strange man tapped Winston on the shoulder took a briefcase,

[It was during the moment of disorder while the posters were being torn down that a man whose face he did not see had tapped him on the shoulder and said, " Excuse me, I think you've dropped your brief-case. " He took the brief-case abstractedly, without speaking. He knew that it would be days before he had an opportunity to look inside it. ]