I didn't assume that you meant exactly five, especially in view of
partner's plays and that from my experience that seems an unusual
treatment. However, if NS assure us that exactly five is their system
then maybe West will rely on his partner relying on that and
consequently signal in some different way. I don't think I could bring
myself as East (or as West) to rely on it though!
> What do you mean by the "obvious club"?
I simply meant that it's obvious to play the club suit; I didn't mean
either club in particular. Since it's posed as a problem I did
consider the signalling aspect of one club or the other, but concluded
there's no point because (a) partner doesn't know I have 4 clubs
anyway so won't be able to read a signal, and (b) partner won't need a
signal anyway. Admittedly that's predicated on the 6-spade idea.
There's no harm in choosing the club 10 but I don't see how it can
help. Come to think of it while I'm grasping at straws to find a
reason however improbable to support a choice, maybe partner cleverly
led low from a doubleton in which case the 10 would be a losing play,
subverting partner's brilliance.
If declarer has only 5 spades then I guess he's already down in the
black suits and if anything matters we have a heart coming as well for
down 2. I don't see any hand where a red shift from me is helpful, but
even if you show me one I don't think I would ever at the table risk
letting a 6-spade declarer make the contract just for a notional
chance of the 3rd downtrick against a 5-spade declarer.
But show -- what have you got?
Charles