The bidding: North, with his 18 points, no five card major and equal length in the minors (Not 3-3), opens one diamond. His partner replies one spade. North knows they have enough for game, but cannot bid notrump with a singleton in partner’s suit. He makes a jump shift into clubs showing 18 points. This is forcing to game and shows 5-5 or better.
North has other strong bids in his arsenal such as a two club opener, a reverse and a jump in notrump. His hand is not good enough for a two club opener. He cannot do a reverse because the lower ranking suit is not longer and he cannot jump in notrump because of the singleton in partner’s suit.
One improves one’s bidding immensely by refusing to run to notrump without notrump distribution.
South, after his partner made a jump shift, knows they are in the ball park of a small slam or even a grand slam. He asks for keycards over three clubs so clubs is the assumed trump even if they never plan to play there. North shows two keycards with the queen of clubs.
South asks for kings by bidding five notrump. Asking for kings promises that the partnership has all the keycards. One asks for kings only when trying for a grand slam and one would not do this missing a keycard including the queen of trumps.
North has one king and South counts his tricks. He has two spades, one heart, four or five diamonds and five clubs. He can assume partner is five-five in the minors. If North were six-five, he would bid seven notrump once his partner shows all the keycards. Eleven tricks in the minors and two aces make thirteen tricks. However, North is five-five and can only count to twelve tricks.
If North asks for keycards and kings, he can get to seven notrump. It is usually important that the strong hand does the asking for keycards. Here it is not possible. South must settle for six notrump because he does not know about the queen of diamonds. I would not blame North for correcting six notrump to seven notrump. After all, it is the correct bid.
The Lead: Against a slam, one likes to lead an ace in a suit not bid by the opponents or the top of touching honours. West does not lead the Queen of spades because it was bid by an opponent and leads the top of nothing in hearts. One never leads from unsupported honours against a slam.
The play: Declarer wins the ace of hearts and claims 13 tricks.
The Result: 6NT+1 for +1470.