Neither side vulnerable.  
North deals.
                              North
                              S: A 4 3            
                              H: A K 8 5 4   
                              D: A Q J 6     
                              C: 7   
            West                             East
            S: J 2                           S: 8 7          
            H: J 10 9 2                      H: Q 7 6      
            D: 5                             D: 10 2              
            C: J 10 6 5 4 3                  C: A K Q 9 8 2
                              South                         
                              S: K Q 10 9 6 5
                              H: 3          
                              D: K 9 8 7 4 3
                              C: Void     
          The Bidding:  
                  North    East    South    West                  
                   1H       2C      2S       4C 
                   4S       5C      5D      Pass
                   5S      Pass     Pass    Pass
          Opening lead: JC
     At a local duplicate game last month, this hand was played
nine times.  The North-South score was either +510 or +440 with
one exception where there was obviously a problem and a diamond
partial scored as +190.
     What kept all of these pairs out of either makeable grand
slam?  The opening bid was very normal, as was the two club
overcall.  South has a number of choices.  A negative double is
forcing but really does not accurately reflect his holding.  I
think that a three club cue-bid would be correct.  This shows
either  a limit raise or better in hearts, or the start of some
other forcing auction.  
     I suspect that most players in the West seat would bid four
or five clubs.  I think that North should bid four or five
diamonds at this point.  If South has hearts this will not be a
problem and if South does not have hearts he will know that North
has a strong hand with both red suits.  A double is also
acceptable but if South leaves this in for penalties they will
only defeat five clubs by three tricks which is only +500, which
is just not enough.
     After five diamonds, I vote for South to either bid five
spades or six diamonds.  It is likely that North will pass five
spades so I favor six diamonds.  This is not the optimal
contract but in view of the interference, it has to be a good
spot.
     Even if you consider South's two spade bid to be forcing, it
will be hard to ever really describe the power in the South hand
without making a cue-bid.  These are difficult hands but you have
to be ready to deal with them when they come up.   
_________________________________________________________________