South opened One Heart and North responded 2 No-trumps (agreeing hearts and forcing to game). South's next bid of Three Clubs was something of a surprise to North, for it showed a clubshortage and an interest in progress. North cue-bid Three Spades, South co-operated with Four Diamonds, and North repeated his spade cue-bid.
Next South showed his first-round club control with Five Clubs, and North bid Five Diamonds. South's jump to Six Hearts ended the auction, for neither partner held third-round diamond control. Very elegant, and it was clearly the right contract.
West led 2Q against the slam and declarer ruffed East's ace. He drew trumps and tested the spades. When they proved to be 4-2, he ruffed the last spade and turned his attention to diamonds. However, his play of the ace and another was not a success and East came to two diamond tricks to defeat the contract.
It is true that South would have been home if the diamonds had broken 3-2, and also if West held four or more in the suit, but he had missed a foolproof safety play. He should start the diamonds by leading low from dummy. Suppose East plays low - then declarer puts in the eight. Should West win the nine, he must either concede a ruff and discard, or return a diamond.
If, as may well happen, East plays the nine on the first diamond lead, South takes his ace and leads a low diamond, inserting the 10 if West plays low.
Then, again, South is home whatever the diamond break.
East-West game; dealer South
4A K 5
!Q 10 8 6 3
#K 10 4 3
4J 9 7 2 410 6
!7 5 !2
#6 #Q J 9 7
2Q J 9 8 6 3 2A 10 7 5 4 2
4Q 8 4 3
!A K J 9 4
#A 8 5 2