After expertly demonstrating the “duchess slant” at numerous royal events in the past, Meghan seemed to innocently forget the pose (at official engagements royal women are supposed to cross their legs at the ankles or put both legs off to the side to maintain poise and posture) when taking her seat beside Prince Harry and Queen Elizabeth at Buckingham Palace to celebrate a group of young leaders from across the world.

At first she accidentally crossed her legs, but she quickly recovered, uncrossing her legs at the knee and slanting them to the side.

According to proper etiquette, which sister-in-law Kate Middleton also follows, royal women keep legs and knees together, although crossing at the ankle is fine.
