Movement is a feature of civilisation: from one country to another, one home to the next, people have always moved, constantly in search of opportunity. And any market watcher will tell you it's very much a feature of the legal industry. Partners switching allegiances in a heartbeat.

Gone are the days when a partner would remain at the same firm for the entirety of their 30 or 40 year career. A few exceptions might include, say, Slaughter and May in the U.K. or Wachtell Lipton Rosen & Katz in the U.S.