IMPS, 64 board match.
This was an interesting hand for a couple of reasons in the Chairman's Cup final. It was board 17 (rotated for convenience in case some SB posts that Board 17 is dealer North). The auction was brief but not uneventful in the other room, when South passed and North opened a strong NT. South, Håkan Nilsson, bid Stayman, and over 2H bid 3NT. Just as West, Lamford, was passing, South said "I have made the wrong bid". West asked if he meant that he had made a mechanical error; South confirmed that he had, so West allowed a correction to 4♥ and all passed. As Vugraph reported:
vugraphzed: Håkan first placed 3NT on the tray. Director called.
vugraphzed: Director ruled it was too late to call. 4♥ is the bid.
That is not quite right. West called the director when he saw dummy (South at his table), but the director ruled that the change of call stood as the auction was over. Declarer made 12 tricks and Lamford, noticing that the correction to Four Spades was cold, let it go rather than risk not being asked back in some future year by making a fuss and trying to gain from some inexplicable non-bridge error! And no IMPs were at stake, as the play in 6H is the main point of the post. How do you play it on the jack of diamonds lead, which Michael Byrne received? I don't think the meaning of the auction matters much, but I cannot explain it anyway!