Not too Wise


K 8
J 4 3
A K 9 6
J 8 5 3
J 6 3 10 9 7 2
9 8 5 2
10 8 4 3 2 J 7
A Q 6 K 10 9 7 4
A Q 5 4
A K Q 10 7 6
Q 5
2Vul: None

EastSouthWest North
Pass 1 Pass 2
Pass 4 NT Pass 5
Pass 7 All pass

EastSouthWest North
Pass 2 Pass 2 NT
Pass 3 Pass 4 NT
Pass 6 Pass 7
All pass
Two pairs kicked away a perfectly lovely little slam, each after going to 4 NT, presumably to check for aces, of which they are missing one, as you've no doubt noticed. Which doesn't augur well for a grand slam. The second bidder's response to 4 NT is completely incomprehensible. I believe I've read somewhere that a void warrants a jump to 6 in that void in response to 4 NT, but that was hardly the case here. So there's no explanation for this that I can figure out. Indeed, the number of aces isn't even correct, even if the responder meant to say 5 instead of six. Where's there any percentage in misleading your partner?
The first pair was undoubtedly playing Roman Key Card Blackwood. If the reader is unfamiliar with that convention, I have discussed it here (scroll down past the second horizontal bar). Or were they both? North's response would be correct playing RKC and assuming diamonds are trump. (A one-time partner suggested, reasonably enough, that if we haven't shown agreement on a trump suit, it'll be the last bid suit.) His bid would then show two "aces" (the trump king counts as one of five), without the Q. (With two plus the Q, one bids 5 spades.)
But if they're both playing RKC, South would then know that they're missing one of five aces and would surely not want to bid grand slam. Would he? But I've gotta suspect that South was playing straight Blackwood, while North was playing RKC.