BRIDGE NOTES: A subtle manoeuvre ensures grand slam

The age old dictum that a grand slam is bid only and not played because of foolproof all thirteen tricks are available without involving finesse or any gap. Hence such a deal is honoured by opponents in surrendering to the bidding side.
But such a distinctive feature may fall short of requirement in some cases, when the partnership ventures into bidding grand slam in the heat of the moment on marginally awkward placing of some honour cards or just insufficient value for the bid. In some cases the partnership prefers to bid and play grand slam in no trumps rather than a five card minor suit in either hand.
In most of the instances fit for a grand slam bid may come through in conformity with the famous dictum but some times the deal and the composition of the cards may delude the partnerships intentions to make a grand slam.
Such a deal was distributed to a pair in North American Championship in the team event some time back. A reasonably experienced pair having match points of middle order to its credit reached grand slam which in most other systems was perfectly justified. But the two queens held by the opposition caused a problem and put the sound contract of grand slam in jeopardy.
THE COMPLETE DEAL AND THE BIDDING IS INDICATED BELOW:
(1) SIMPLE BLACKWOOD
WEST LED JACK OF CLUBS
When the dummy came down south took a critical look at the combined hands and found out that there were only twelve tricks on top. Now his problem was to create a thirteenth trick to fulfil his contract. Then he had a problem of finessing the queen to meet his commitment and there was would the no problem if he could find the heart queen or the spade queen at the right place to reach the grand slam.
But the question was which queen he could trap which was a sheer guess so in trying to avoid a guess work he opted for a manoeuvre Having decided upon the line of play he won the lead with the king of clubs and moved ace of diamonds and continued with the diamonds suit ending in dummy. In this exercise he was watchful of the discards that the opponents made which helped him a great deal in locating either the queen of spades of the queen of hearts.
He found out that both the opponents discarded spades and clubs but none the queen of hearts.
So by a process of deduction south found out that the queen of hearts was with West which was a strong presumption to convince him to finesse the jack of hearts in dummy and made the contract with flying colours.
In this manner south avoided taking a blind finesse even though there were options that if the heart finesse failed he could rely on spade finesse to make his contract.
But playing intelligently he avoided the risk of going down by locating the adverse queen to the applause of the gallery.
DEALER: NORTH BOTH-SIDES VULNERABLE:

================================================

North          West          East          South

------------------------------------------------

S 8            S 9763        S Q 10542     S AKJ

H AJ 875       H Q 63        H 42        H K 109

D KQ 1072      D 83          D 94        D AJ 65

C Q 8          C J 1095      Q 7632       C AK 4

================================================

THE BIDDING:

================================================

South          West          North          East

------------------------------------------------

2 C            Pass          2 H            Pass

2 NT           Pass          3 D            Pass

4 D            Pass          4 NT (1)       Pass

5 S            Pass          7 D            Pass

7 NT           Pass          Pass           Pass

================================================