I would have thought that if all North wanted was a diamond control for slam, he'd have jumped to 5H earlier in the auction; South has nothing good about his hand other than the diamond control so I think he's wrong to cooperate.
ATB slam
#22
Posted 2010-February-08, 15:46
South also has the ace of spades, which is a valuable card opposite North's 4♠ cue. I think it's ok to cue a second-round diamond control at the 5-level when you have an unshowable and working first-round control (usually the trump ace). Also, I believe South should cue a club control over a diamond control because if North only needed a diamond control for slam, North could have asked for it by raising 4♥ to 5♥. So count me in the camp that says 5♦ implies no club control.
Eugene Hung

Help
