It became obvious watching the semi-final and final of the 2015 Men's Graded Triples that players were frustrated by the actions of their opponents in moving around when they were not in possession of the rink.
Law 13 is clear on who has possession of the rink. Law 13.1 states possession of the rink belongs to the team whose bowl is being played. Law 13.2 states possession of the rink changes as soon as each bowl comes to rest, allowing for the marking of a toucher. Law 13.3 outlines the options that an umpire can take by their own observation or by the skips if they feel a player is being interfered with or annoyed or distracted in any way.
At the mat end players should keep still and stay one metre behind the mat if not in possession of the mat. At the head end players should remain still and behind the head once a bowl is being delivered and not signal the position if their team is not in possession of the mat.
WPH Chairman of Umpires