No strings pulled
My friend was in a long queue for Avis at a regional airport in France. He vaguely recognised the couple in front of him, admiring the lady's shapely legs, and then he remembered who they were: the Middletons! Eventually he plucked up the courage to speak to them with this opening gambit:
"I thought that the whole point of having a son-in-law like yours was to avoid queues like this!"