Source: Aces on Bridge — Daily Columns
This deal from the 1993 Epson Simultaneous Pairs was played at the top of the Post Office Tower in London with a host of dignitaries and assembled top players. It demonstrates the principle of not giving unnecessary information to declarer to allow him to count out your hand, an idea espoused by the great Jean Besse, who referred to the irrelevant small cards as neutrinos.
At the table North-South (who were playing weak no-trumps) reached six no-trump. On a heart lead declarer cashed the club ace and king, then ran the hearts as East discarded enthusiastically in diamonds. West — a former World Champion — threw three diamonds, and declarer played a spade to the queen and king.
West now returned a low club to the queen, East throwing a spade and South, a diamond. So far so bad from declarer’s perspective, but the diamond ace forced a spade from West. Now declarer knew that both defenders had only one spade left, as East was guarding diamonds and West clubs. He could thus play a spade to his ace in complete confidence.
Do you see the small defensive error? West knew she was going to have to discard a spade eventually, so she should have thrown one on the sixth heart. Then declarer does not get the complete count on the diamond suit and has to guess the spade suit in the ending. By showing a void in diamonds, West turned declarer’s hypothetical count on the deal into a sure thing.