Shirts should be green or brown, like the well-cut William & Son shirt in the aptly named “grouse” colour. Grouse, like other birds, see in the ultraviolet spectrum. White, then, is incredibly easy for them to pick out. A white shirt collar is shouting “avoid my butt”. The thrifty can bulk-buy Rydale sporting shirts at the Game Fair (the “Poacher” one, in particular).