Journalist Robert Quillen wrote, "Discussion is an exchange of knowledge; argument an exchange of ignorance." Do you agree?
The key word in that sentence for today's deal is "exchange." How is that relevant when South is in four spades, and West leads his diamond?
West's unfavorable-vulnerability pre-empt would have horrified the old-timers, but no one passes with a long suit these days. After two passes, South was tempted to bid three no-trump, which would have worked well.
When an opponent opens with a pre-empt, then leads a side suit, that card is a singleton. The original declarer knew that, but still had his eyes closed. He hoped for these 10 tricks: five spades, two hearts, one diamond, one club and a club ruff. So, he won with dummy's ace, drew two rounds of trumps (ignoring the significance of West's jack), cashed the club ace and ruffed a club. However, East overruffed and led the diamond king. Declarer ruffed and played three rounds of hearts, but East won with his queen and led his last heart. South had to lose the overruff, one heart and two clubs.
Assuming West's spade jack wasn't a clever falsecard, when South led the second club, he should have discarded a heart from the board, exchanging the dangerous club ruff for a safe heart ruff. West would have shifted to a heart, but declarer would have won with dummy's ace, played a heart to his king, ruffed his third heart, ruffed a diamond, drawn East's final trump and lost only three club tricks.