(Porthcawl Bridge Club)
Contract 4♥ by South
West leads ♦J, and East covers dummy’s king with her ace. Declarer ruffs with ♥2. East doesn’t see the ruff (she thought the ♥2 was the ♦2), and now plays the ♦Q. South knowing that he has won the previous trick, and also not noticing East’s ♦Q, now plays ♥K.