No, I didn't hear an announcement about the understudy going on, and we were sitting there about 15mins before the curtain went up. There may have been a note of it in the main foyer, I suppose. I also didn't see any photos of our guy outside the theatre - only lots of the Lindsay Duncan poster in the big hat. Again, I might have missed pics of the rest of the cast in the foyer area where I didn't really go...maybe they are expendable!!!