Are there choices here? Continued

The problem presented yesterday, from our last match against Cayne was this:

WEST KQ108 9432 10972 J
	SOUTH J6532 K6 Q5 KQ62

You are West, sitting over dummy after this auction:

West….North….East….South
Pass…..1D…….Pass…..1S
Pass…..2C…….Pass…..3C
Pass…..3NT

Partner leads the S7 to your ten. What should you do now?

I’m both surprised and relieved that nobody came up with the answer:

	NORTH 4 AQ107 AJ64 A973
WEST KQ108 9432 10972 J		EAST A97 J85 K83 10854
	SOUTH J6532 K6 Q5 KQ62

I continued a spade on the basis that if declarer had nine minor tricks and partner had the heart ace, we need to cash out now. In fact, what you have to do is shift to a diamond, which was my other thought. Maybe this is just odds: it’s more likely that partner has both minors stopped than the heart ace? Continuing with a spade meant that declarer got to keep playing spades with a view to squeezing partner.

Shifting to a heart is no good. When declarer continues with a spade, if you win it your side has only three spade tricks so declarer can develop diamonds. If partner wins it, then he has nothing effective to do. He exits, declarer plays another spade and that is the end of that.

Is there a useful clue in the opening lead? With four hearts partner might well have led one. Maybe that affords the presumption that declarer is 1444, and now the diamond shift is obvious as declarer can’t be cashing out in the minors.