This was a Baron Barclay's problem.
Both vulnerable, I was sitting South after three passes with the following hand: (All x's are 6 or lower). (s) AT7x (h) Kxx (d)9xx (c) AJX.
I elected to pass. I have 12 high card points but no five card suit. And my distribution is 4-3-3-3, so I deduct one point. I have one T, one 9, and one 7, but less than what was expected in intermediate cards (no 8s).
My second choice, with the "right" partner, would be 1 spade. Rule of 15, opposite a passed hand in third or fourth seat. Switch my hearts and spades and I would just pass; the other side is more likely to have spades.
But the answer given in the problem was one club. The two partners got to a precarious, but makeable 3 spade part score because partner had, (s) KJ8x (h) Qx (d) KT9 (c) T87x. Partner had his "quota" of 9 hcps, something extra in intermediate cards, and above all, four pretty good spades.
Was this a "lucky" result that I did well to shun? Was this a "natural" result of an opening one spade bid? Or should I follow Baron Barclay's supposedly expert line and bid one club?