There were mistakes made on both sides of the hand. Mine was less eggregious, as no other tables bid the slam.
I was sitting East on this deal. My partner and I play Berkowitz and Manley Precision. So 1C was a big hand. 2S set trumps and asked p for trump length and controls. 3C showed 5 spades to one of the top 3 (meaning a trump loser). 3D asked for diamond controls. 3NT should have screamed 2nd round control, but I can't count, apparently, and read it as third round control. So I signed off in the Spade game.
The rest of the auction should have gone:
4C*-(P)-4S*-(P)
6S-AP
4C = control in clubs; 4S = 2nd round control
I have no idea why South felt it necessary to open his mouth. On a previous hand, he bid hearts three times with a 12 count and only 5 hearts, so I guess I shouldn't be surprised. Partner left the double in, and when it was all over, 5H was down 7 doubled, for a tidy 14 IMPS. More than if we bid slam, but slam still would have been a top.
I just thought everyone might like to see this one.

Help

1C*-(P)-1S-(P)
2S*-(P)-3C*-(P)
3D*-(P)-3NT*-(P)
4S-(P)-P-(5H)!
DBL-AP