A couple of random hands are dealt and then this appears:
and the auction runs:
West might have opened a game-forcing 2C, although technically, the powers-that-be state you cannot open a game force without a minimum of 14 HCP (madness on a scale of politicians there).
East's 2D was Fourth Suit Forcing, West's jump to 3S intended to show at least 6-5. When East then shows preference for clubs, West's 4S is trying to get across the 6-6 shape. This distribution is so rare, it is hard for partner to believe that it exists. East bid 4NT and learned that West held only one key card, and then with her 5H bid asked if West held Qs. Discovering that she did, East bid the Grand Slam.
As the cards lie, 7NT will be fine, but 7S will seem a lot safer from East's point of view since, if West does not hold Qc, or even Jc, the side suit can be ruffed out and made good. However, if I were playing Duplicate Pairs, I would bid 7NT on the East hand. The key bid to take into account there is West's jump after 4SF to 3S - that shows a strong hand and, without three aces and Ks, surely West's suits must be pretty solid otherwise.
How would you and your partner have bid these two hands?