It's hard to imagine that
Kate Middleton can walk among the commoners unnoticed these days -- but that's exactly what the Duchess did when she visited the National Portrait Gallery in London Wednesday. The 29-year-old spent the afternoon touring the contemporary collection downstairs with a small group of curators, an onlooker tells Us Weekly exclusively.
"She was dressed all in black -- she must have been boiling because it was a really hot ...