This is fundamentally a problem in counting the hand. Declarer (very kindly,
thank you!) played the suits in order, allowing you to tick them off, one by one.
She opened spades, so, you expected her to have at least 5. When it took 3
rounds to clear the spades (you had 2, dummy had 3 and partner showed up with 3),
you know that it was EXACTLY 5.
She then attacked clubs, showing out after 2 rounds (pitching a diamond on the 3rd),
so, at this point you KNOW that she started with 7 black and 6 red cards.
She proceeded to hearts, playing 3 rounds, displaying disappointment when
you had only 2. Partner and declarer followed to all 3 rounds, so, at this point
you know that there is only 1 unknown heart (the queen!). Does declarer or partner have it?
Partner MUST have the missing heart. If declarer had 4 hearts then she's made her contract
with 5 spades, 3 clubs and 4 hearts, but, here she is, stewing about what to do
next. She MUST have started with 3 diamonds originally. Her hand looked like this:
♠ AKQxx
♥ Axx
♦ ??x
♣ Kx
What could those 2 unknown diamonds be? There are 4 possibilities:
a. KQ
b. KJ
c. Kx (x is ANY card but the Q or J)
d. xx
In (a), (c), and (d) it doesn't matter what you do!!! (a) is obvious. She gets
one diamond trick and you get the other. (d) is just as obvious. She doesn't get
ANY diamond tricks.
(c) is not quite as obvious, but, put yourself in declarer's place. You lead a
low diamond from the board towards your Kx. What are you going to play? You
really don't have a choice....you MUST play the king! It either works or it
doesn't. She gets one diamond trick and you get your ace, now or later.
(b) is the SINGLE critical case, the ONLY case where you can give declarer a
losing option. If you play low SMOOOOOOTHLY, without hesitation, what does she
do? If the ace is on her right, she wants to play the king, but, if it's on her
left, she wants to play the jack. Which door does she pick....the Lady or the Tiger?
The bottom line is: if you jumped up with the ace or gave any clue that you had a
problem then you get a zero for the board, for no other pair was in the 31 HCP slam.
If you played a low diamond, without a tremor, then you have a 50-50 shot at a
top.