South won the heart ace, drew trump and claimed thirteen tricks, since a club could be parked on a long diamond, N-S +710.
A club lead would have netted the defense one trick but twelve tricks were a lock. West's cue bid was Top and Bottom revealing hearts and clubs. East was confronted with a bidding decision. Should be advance in hearts or clubs and at what level? From his perspective, the opponents were odds on favorites to make a spade slam. He, therefore, chose to bid five clubs rather than six clubs, a move that might stampede the opponents into a spade slam. East would get another chance to re-assess the situation in the event that South ventured six spades. The vulnerability was favorable to E-W where a seven level sacrifice would yield a huge profit. South could score a heart ruff but NS would score only four tricks (+800).
South surely considered an advance to a spade slam but East's leap to five clubs had prevented him from employing Blackwood. He needed partner to own a rounded suit ace and the king of diamonds for success but North would not always display the necessary honors.