Bridge & other card games/response to partners 1 NT after intervention by LHO
My partner opens with 1 NT. his LHO bids 2 diamonds. Without this intervention, I would have answered 2 diamonds to show a Jacoby transfer to hearts. Should I bid 3 diamonds? Question is if my partner would understand it. If I were to bid 2 hearts, my partner's strong cards would be the dummy.
Would appreciate your answer and thank you for your help.
There exists a treatment known as "mirror doubles" or "stolen bid doubles". A double of the interference by the opponents at the 2 level basically says that the opponent "stole" the bid that you were about to make.
After an opening 1NT bid if an opponent bids 2C then double is Stayman, if an opponent bids 2D then double is a transfer to hearts and if an opponent bids 2H then double is a transfer to spades. And further, all higher bids retain their same meaning as though no interference had occurred. The goal using this agreement is to make the opponents go away. Just as if they were silent.
However, many experts feel that this convention is not a very good idea since it makes it difficult to double for penalties to punish the opponents. Most of the experts recommend to just bid 2H yourself if you wish to compete in hearts (and bid 2S to compete in spades). It's true that your partner's hand will be the dummy but competition by the opponents usually makes your auction more difficult and you have to cope as best as you can.
Bidding 3D is not used for this purpose. Aside from forcing you up to the three level, the cue bid is usually meant as Stayman to inquire about unbid four card majors 2C is no longer available) and is done with a hand strong enough to bid a game.
The exception is if the opponents overcall 2C. Then it is a good idea to use the double as Stayman and the other 2 level bids as transfers.