The bidding: It is always nice to have a moose (a big hand) and partner opens the bidding ahead of you. You have two thoughts, small or grand slam and you do not want partner to pass out the bidding below one of those two spots.
South opens One Spade and North bids Two Diamonds, a new suit at the two-level showing ten or more points, in this case, much more. South responds Two No Trump with a minimum opener with stoppers in the unbid suits.
North bids his second suit, Clubs at the three-level. While a new suit at the two-level is ten plus, a new suit at the three-level is forcing to game.
South could just bid Three No Trump, but that is just lazy bidding. On the way to Three No Trump he shows partner he has three diamonds by bidding partner’s suit. A direct raise usually shows four cards, and a delayed raise usually shows one card less.
North has heard enough and asks for keycards. Partner has one or four keycards (Aces and the King of Diamonds). North bids Five No Trump showing possession of all the keycards including the Queen of trump. Normally, people will play that Five No Trump asks for the number of Kings, but I like it to tell partner to bid his lowest ranking King. This is called specific King asking system.
South says he has the King of Clubs which does not deny the possession of a King in a higher ranking suit. If South had bid Six Diamonds, that would show the King of Diamonds without the King of Clubs.
North bids Six Hearts asking partner if he has specifically the King of Hearts. South answers Six of the trump suit (or Six Notrump if the trump suit is passed) to say no and Seven of the trump suit to say yes. He says yes and North can count 13 tricks and places the contract in Seven No Trump. Who wants a ruff on the opening lead against Seven Diamonds? Not North or South.
The Lead: A Diamond lead is a must because it gives away nothing. Unless you have an Ace to cash, a passive defense is the best. A Diamond lead is safe because it is known that the opponents have the top three Diamond honours and an eight or nine-card fit.
The play: Declarer counts to thirteen, claims and leaves the table to get a coffee while the opponents survey the claim.
Result: Seven No Trump making for +1520.