Declarer ruffed and drew trump to continue with the ace and king of clubs, exposing the 4-1 break. A club loser was now inevitable and the contract was just home, N-S +600. A diamond slam was indeed a viable proposition but South was not willing to venture slam after North eventually raised diamonds. South assumed that partner would hold wasted spade values which was not really the case on this occasion. North's display of the club ace-king and the king of diamonds were the perfect honors to make slam a good bet.
At quite a few tables, North became declarer at 3NT where the opening lead was critical. At one table, East selected the heart queen where North emerged with thirteen tricks. At a few tables, East began with a fourth best spade and West played three rounds of the suit where North recorded ten tricks. Curiously, not one E-W pair was able to defeat the nine-trick game declared by North.
Frankly, it comes as a great surprise to me that North was allowed to play 3NT at any table since South held twelve minor suit cards.