I agree that N should open 2
♣. I hate doing so on two-suiters, but we have a Losing Trick count of 3!!!!(edit I had misread the hand as AKQxx in both blacks so had posted a LTC of 2...but 3 is still very, very good) Since the typical minimum 1
♠ opener has a LTC of 7, we are about 5 tricks north of a minimum, and that is way too much to ever hope to convey. We have good play for grand opposite xxx Kxx xxxx xxx. I will risk missing games by opening at the 1-level, but risk a grand? Not for me. heck, I bet Art would open 2
♣
My experience has persuaded me that the best approach for responder, when holding an unusual hand, is to bid 2
♦ almost automatically. This works best in a method in which 2
♥ is an immediate negative, since 2
♦ establishes a gf, and allows for later, below game, bids to be forcing.
Since S is driving to slam once partner bids 2
♣, I think S should try to allow opener maximal room to describe. For example, should opener rebid 2N, which is a common move after 2
♣, S is well placed (assuming reasonable methods) to set diamonds and keycard. Whereas if he bids 3
♦, and hears partner bid 3N, the auction will likely get complex absent special agreements....how does responder set diamonds and keycard? Maybe some partnerships can, but many won't be able to do so.
As it happens, nothing works well here.
2
♣ 2
♦
2
♠ 3
♦
4
♣ 4
♦
4N 6
♦
4N is natural (please, if 4N is some form of blackwood for you, please reconsider your methods)
Note that on this auction, were opener to hold AKQxx AQ Q AKxxx, he could and should bid 7
♦.
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari