Posted 2014-January-31, 15:33
This is a very old theme. The simple answer is that at imps or at rubber or total points one pitches the spade A.
You cannot possibly have a stiff spade! Not only does that give S an impossible number of spades (clearly S is not playing roman/tartan jumps and has long diamonds) but if it were stiff, it is always going to score a trick.
So this is a play that is sometimes referred to as an 'alarm-clock' signal...intended to wake partner up.
This was almost certainly taken from some old book on defence because in the modern game, S's 4♦ would show spades and diamonds.
Note that discouraging spades won't do the trick.....partner will think that we want a club more often than that we want a diamond. Picture S with Ax Qxx AKQxxxx x, or the same hcp but 2=3=6=2 shape. Now, that may seem like a bad example, and maybe it is, but hands taken from old books on play will often be based on auctions that look silly to modern eyes (and, yes, I see that there was a weak 2 involved, but they've been around for more than 50 years now).
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari