[WellSpyder]

Sometimes (maybe more often that I like to admit!) I find it hard to envisage what partner might hold to explain his bidding....

Anyway, you hold ♠A652♥A5♦KQJ75♣Q7. Scoring is imps. Partner (a good player who is occasionally given to flights of fancy) deals at game all and passes, as does RHO. This is the land of 4-card majors and the weak NT, so you open 1♦ - which will always be at least a 4-card suit, and more often than not a 5-card suit. Oppo are silent, and partner responds 4NT!

There is a reasonably widespread school of thought that a 4NT response to an opening 1-level bid should be 4-ace Blackwood rather than RKCB, since you can always bid something else first if you want RKCB but there isn't any other way simply to ask for aces if that is all you want to know. But that argument surely only applies to an unpassed hand - so have you discussed what 4NT by a passed hand means in this sequence???

Maybe you don't think this is a particularly high priority for partnership discussion since partner can't possibly have a hand worth 4N when he has passed as dealer. Nevertheless, that's what he has done! Fortunately, partner is not of the school that believes in 4-ace Blackwood, so you meekly reply 5♣ to show 0 or 3 key cards, and the next bid you see is 7♦ from partner!

I can't pretend to have any idea what is going on, but fortunately I'm not called on to make any more decisions before seeing the dummy...

Partner's hand:

Spoiler

♠9 ♥3 ♦A10962 ♣AK6542. He doesn't believe in opening such hands with the shorter suit, and felt that after opening 1♣ it would be very difficult to show the fifth diamond, so preferred to wait and probably come in with a two-suited bid. It was perhaps fortunate I didn't hold ♠KQJx ♥KQJ ♦QJxxx ♣x, but I can see the temptation to bid a simple 7♦.....

[P_Marlowe]

How did partner reason, that you have to have 3 KC?

[WellSpyder]

P_Marlowe, on 2013-January-16, 04:08, said:

How did partner reason, that you have to have 3 KC?

Good Q. I don't think he could really be sure (see the example I suggested in the spoiler, for instance). 2 possible reasons for the immediate jump to 7♦:

1) Sensing my bewilderment at how a passed hand could possibly be worth RKCB, he couldn't resist jumping to 7 for the fun of seeing my face (it wasn't a particularly serious game); or

2) Although the normal expectation would be that he would sign off and expect me to bid on with the higher rather than the lower number of key cards, he perhaps thought there was a risk I wouldn't do it in this case for the same reason that I wouldn't really think a passed hand could be worth RKCB.

Whatever the reason, I wasn't going to argue with success.....