Teams.
1NT: alerted
dbl: opening values
rdbl: alerted: asks partner to bid 2♣.
Before the match starts EW duly alert that they play a 9-13 1NT in first and second seat while non-vulnerable.
However, on the twelfth board West alerts the third hand 1NT opening. South assumes a weak NT and does not ask.
NS play a different defence against strong NT than against a weak NT: Against a strong NT they play DONT. The double now merely shows values.
Before the play starts East explains that his NT was strong and that his partner should not have alerted. No one calls for the TD at that time.
The play:
4th highest diamond for the Ten and Queen. East returns a diamond, after which South clears the diamonds by playing Ace, King and a small one. On the ♦K North plays the ♣2, a possible signal for hearts (they play that an odd discard is a strong positive signal, an even card is a weak Lavinthal preference). After South fails to continue spades 3NT is made.
After the play the TD is summoned. NS state that they might have found their spade fit with the correct explanation (a direct 2♦ over a strong 1NT shows 54 diamonds and a major) after which it is unlikely that EW will play 3NT and if they do, that NS will have a better chance of beating 3NT.
The TD asks after EW's methods: West would have passed the first time after a 2♦ internvention because bidding on the three level would show a stronger hand. She might have bid 3♣ after a projected auction of 1NT-2♦-pass-2♥-pass-2♠-???
How should the TD rule?
If you want to know; the result on the other table was 3♣=