May 5th saw a change in Google's policy with respect to the use of other people's trademarks in your PPC advertising. This means that Eversheds could set up a PPC campaign and use the phrase Clifford Chance as one of the keywords it is bidding on.
Now, Eversheds cannot misrepresent themselves in the ad text that goes along with that keyword, but setting up a Campaign or AdGroup targetting all of its competitors It's all legit and completely above board now.
See Google's full explanation of this change at http://adwords.google.com/support/bin/answer.py?answer=92877&topic=10615