Also in London, also from Dec. 10, a photojournalist named Jesse Oldershaw was stopped and searched while covering protests in front of the Greek Embassy where people had gathered in reaction to the unrest in Greece.
At 4:25 of the video, a police officer, rather preposterously, asks if Oldershaw has a knife in his back pocket. As he is being directed off to the side, Oldershaw is screaming out, “Why am I being stopped and searched by the police for a yellow pen in my bag? Everybody can see the yellow pen!” and “I’m press, why am I being stopped and searched by the police at a demonstration?”
Oldershaw continues to give a play-by-play of the incident and at one point asks the police straight out their reasoning when he is protected by law to be doing what he’s doing. They largely ignore him, but one does seem to give him a ticket.
boywithgrenade.org 
the ‘ticket’ is a record of the stop and search,it is required under UK law for a police officer to provide a reason for searching someone and that the record be kept at the officer’s station:
http://www.met.police.uk/stopandsearch/what_is.htm