There was an interesting ruling at a local club in London on this hand. South opened a psychic 2♥ and the opposition were soon in 3NT and South tried a speculative double. North was rather confused by this, and there was certainly no agreement to play a Watson double of 3NT to ask partner not to lead one's suit, but as a matter of bridge common sense North decided to lead the ten of spades, and declarer drifted two off. West, whose tufts of hair above his ears reminded one of the secretary bird, quoted part of OB6A3: "<snip> if you play that a double of 3NT asks partner not to lead the suit you’ve bid (Watson), you may not make such a double if the earlier suit bid was a psyche." However, South was ready for him, quoting back 40A3, again verbatim: "A player may make any call or play without prior announcement provided that such call or play is not based on an undisclosed partnership understanding." "The EBU regulation can only apply if we have a partnership understanding on this double - indeed my partner is a visitor from Wales and I have never played with him before. The EBU cannot prevent one from doubling here."
How do you rule?