South opened One Spade, North raised to Two Spades, and, without any preliminaries, South jumped to game. West led the king of clubs against Four Spades and declarer ruffed the club continuation. As it would have been all over if the queen of trumps had fallen in two rounds (a 50 per cent possibility of a 2-2 break with the extra chance of the queen being singleton), South continued with his two top trumps only to find that West still held the queen.
The diamonds had to be tried, so declarer crossed to the ace of hearts and finessed the jack of diamonds (East might have held both of the missing honours). No joy, for West won with his queen and drew a third round of trumps. Then he forced again with a third round of clubs, using up South's last trump. With no entry left to the table for another diamond finesse, de-clarer unavailingly played off his ace of diamonds but the king did not fall and so he had to lose a fourth trick and so go off.
So, what was the alternative? When the first top trump failed to drop a singleton queen, it would not have been a bad idea to lead a low trump from hand. This may cost a trick unnecessarily but it would ensure a trump entry to the table and so enable South to take two diamond finesses instead of just one. This would seem to offer at least a 75 per cent chance of success - a better bet, I think, than South's actual line.