Meaning of this double
E/W are decidely inexperienced players. South is a nationally recognised expert and former Director, North is experienced but on this particular night was unwell.
I was called about this sequence (E/W vulnerable):
West opened a 12-14 NT on a 4333 12-count. North bid 2 Hearts. East, holding (S) ATxxxx. (H)x, (D) KJxx, (C) xx, and would have bid 2H as transfer, chose to double. The double was not alerted. South passed, East bid 2 Spades, E/W ended in 3 spades, making 9 tricks though 10 tricks were available and made at other tables.
South did not ask the meaning of the double. He thought a double in that position was was penalties. East and West were familiar with the EBU convention that doubles of NT are penalty, doubles of a suit are take-out, and do not need to be alerted. South asked me to look at the board (not wth any view to obtaining unfair advantage), saying had he realised it was for take-out he would not have passed (probably raised Hearts).
I agreed with E/W that the double was take-out, and that if there was any doubt South should have asked, and let the result stand.
According to Deep Finesse only 8 tricks were available to N/S in Hearts.
Is there an official EBU line of what 1NT- natural overcall - double means?