Chameleovision

Thanks to a fortunate evolutionary twist of fate, Margaret had been born with independently-directional eyes. 
While unsuspected passers-by would have been in their right to assume that she was looking at the No crusaders at the bottom of Marine Road, she was in fact checking Mariusz's pectoral muscles with her left eye. And a fine pair of pectoral muscles they were too! 
The dark shades were just the final touch to perfect the subterfuge.