[gnasher]

1♦ pass 1♠ 1NT
2♦ pass ?

The 1NT overcall is natural.

Do responder's bids here have the same meaning as without the intervention, or does the overcall change things?

[mich-b]

You're basically asking if 2♥ now should be forcing?
I would say "yes". If you're weak (and would have passed without the 1NT) same reasons for passing apply , only more so :
opener's 2♦ after the 1NT is surely a (good?) 6 card suit.
Agreeing that 2♥ is nf , only "correcting" the partscore , seems to imply you think that you should not explore for (and make) a game once they overcalled 1NT.
While the 1NT bid shows a good hand , I dont think opening side should be giving up on exploring/inviting/making game just yet.

[han]

Good question. Normally i play that 2H here would be an artificial GF, but here I would assume that's off and 2H is NF. We have not discussed this though, and I wouldn't risk it at the table.

Having said that it is a good question, I think that responder will almost always pass or bid 2NT, 3D or 3NT.

[nigel_k]

I definitely would expect the meaning to be the same as an in uncontested auction, unless there was a specific agreement.

[mycroft]

I would avoid saying this in B/I, but I would keep my agreements, because otherwise the people who bid a sandwich NT, "16-18" with 6 clubs and out will eat me alive. Does it happen? Well, it has against me, twice that I can remember (well, once it was a 2434 yarborough, but he was still right, at favourable - he would have taken the same one trick he was getting on defence, for -1400).

[Vampyr]

mycroft, on 2012-January-19, 14:53, said:

I would avoid saying this in B/I, but I would keep my agreements, because otherwise the people who bid a sandwich NT, "16-18" with 6 clubs and out will eat me alive. Does it happen? Well, it has against me, twice that I can remember (well, once it was a 2434 yarborough, but he was still right, at favourable - he would have taken the same one trick he was getting on defence, for -1400).

Interesting. With most partners I play (1♥)-x-(1♠)-x as showing spades, but don't have any other bids to allow for the opponents to have psyched. I wonder what else is out there...

[dake50]

Why did partner NOT double,
NOT leave bid out/Dbl to you?
I'm 70% reliable he fears running clubs
with stops in the 1NT.
He fears your bid out is trouble.
Some thing like 2=3=6=2.
Pass unless 1NT was a joke and you have 12+ hcp.

[jallerton]

gnasher, on 2012-January-19, 06:23, said:

1♦ pass 1♠ 1NT
2♦ pass ?

The 1NT overcall is natural.

Do responder's bids here have the same meaning as without the intervention, or does the overcall change things?

Yes, unless there has been a specific partnersip agreement to the contrary, Responder's bids should have the same meaning as in an uncontested auction. It's still possible for the opening side to have game on here.

[Hanoi5]

What if you want to force? Should you jump? I think you need a forcing bid here.

And what if they're confused, 1NT is sandwich showing a weak hand with the unbid suits and they misalerted? Then we'll be in a pretty bad position without something being forcing.