[VixTD]

I play the Asptro defence to 1NT in a few partnerships, in which a 2♣ overcall shows hearts and another suit, 2♦ shows spades and another suit (at least 5-4). If next player passes, partner bids the anchor suit with 4+ (or 3+ if unbalanced), 2NT with 3-card support and invitational+ values, or the next step without support.

What's the best approach if responder doubles the Asptro overcall?

This is often played as a penalty double of the anchor suit (more rarely takeout), or showing the suit doubled, or general values. Quite often partnerships have no agreement about what the double means, although in that case it will often be made on general values or a holding in the suit doubled.

So, for instance: (1NT) - 2♣* - (X) - ?

How do you play in this situation: (i) pass, (ii) XX, (iii) 2♦?

[gordontd]

Pass shows clubs
Redouble asks partner to bid their longer/stronger suit
Suit bids other than hearts are natural

[RMB1]

Much the same:
Pass = to play if overcaller's suit is clubs
XX = asks overcaller to bid his longest suit, but 2♥ with clubs
2♦ = to play if overcaller's suit is diamonds

[helene_t]

I think that
Pass=to play if overcaller has clubs
2♦=to play if overcaller has diamonds

is redundant.

Gordon's method is simple but I lack a call to ask overcaller to bid his non-heart suit.

What about this:

pass=asks for non-heart suit. overcaller can redouble if hearts are longer/stronger than diamonds, hence 2♦ would show longer/stronger diamonds.

rdbl=to play 2♣, maybe unless overcaller is short in clubs (although this is a little problematic since 2♦ by overcaller could not be either 5-5 or 4-6 or even 5440).

2♦/♥/♠=to play

[campboy]

Much like Robin and Gordon:

pass= willing to play here if you have clubs;
xx= not willing to play here, please bid your better suit (or hearts if you have hearts and clubs);
2♦= to play, long diamonds.

I definitely think this is the right way round for pass and redouble; just because 2♣ is your best fit doesn't mean you can make it. After you pass, partner with both reds can use 2♦ and xx to distinguish lengths if you like.

[VixTD]

Useful replies, thank you all.

I have been playing pass as willing to play there if clubs is the second suit, but wasn't quite sure the best thing to do with the other two. I have been following the booklet by Nevena Senior (with adaptations), in which all she says about redouble is that it means "show me what your hand is about, partner". I have never been sure what that was supposed to mean.

[FrancesHinden]

It depends how sophisticated you want to be.
If you are in danger of going for a penalty, it's helpful to know as much about overcaller's hand as you can. We play the following after 1NT (2m) x:

Pass = pass if you have 4+ cards in this suit AND SEE BELOW
2D = pass if you have 4+ diamonds
2H = pass if you have 4+ hearts
2S = to play
redouble = I want to play in my suit, please bid step 1*

After 1NT- (2m) - dbl - (P) - P
redouble = I have the locally higher suit; other bids in context. This means

1NT - (2C) - dbl - (P) - P
2D = 5 diamonds
redouble = 5 hearts and 4 diamonds
2H = majors (the way we play, longer spades)

1NT - (2D) - dbl - (P) - P
2H = majors, longer hearts
2S = 5 spades, 4/5 clubs
redbl = 4 spades, longer clubs

I think this is still not optimal, because the redouble by responder is somewhat wasted after 1NT 2C x as the only suit you might want to run to is 2D.

An alternative sometimes played is basically as above, but instead redouble shows the other two suits (not the suit doubled, not partner's anchor suit). I think this might be technically better for this particular auction, but we use redouble as 'I've got my own suit please bid step 1' in all these potential penalty-going auctions.

[helene_t]

Frances' structure looks really good.

As for the issue that rdbl can only mean hearts: what about playing

(1N)-2♣-(x)-xx
(p)-2♦-(p)-2♥

as spades with heart tolerance, say six spades (or five very good ones) plus three hearts?