[maris oren]

playing short club system partner opened with 1♣. Opponenr overcalled with 1♦. I have 7 points and 4♠. Should I bid 1♠ or do I need 5 ♠ after opponents interference?

[mycroft]

Traditionally, in this auction 1♠ shows 4. This is unlike 1m-(1♥), where traditionally 1♠ is 5+ and double is exactly 4. Here, you can't double without both majors, so you have to show the 4-card major.

Now, of course, if it is 4 spades, it likely is 0-3 hearts for exactly that reason.

Note: all of this is "traditionally". There are people, even world-class players, who play each of these things differently. They have spent a lot of time, of course, understanding how to bid the hands they can't show the "traditional" way.

[pescetom]

mycroft, on 2025-May-06, 11:52, said:

Traditionally, in this auction 1♠ shows 4. This is unlike 1m-(1♥), where traditionally 1♠ is 5+ and double is exactly 4. Here, you can't double without both majors, so you have to show the 4-card major.

Now, of course, if it is 4 spades, it likely is 0-3 hearts for exactly that reason.

Note: all of this is "traditionally". There are people, even world-class players, who play each of these things differently. They have spent a lot of time, of course, understanding how to bid the hands they can't show the "traditional" way.

I'm sure mycroft will be right for his (large) part of the world.
Here in Italy (and much of Europe, I suspect) the "traditional" rule was that you needed 5 in any suit after interference (and you didn't need both majors to double).
Nowadays things are as he says, although some expert players prefer that 1♠ is 4+ and X is NT oriented (or vice versa).

[mikeh]

Mycroft is exactly right. Think about it this way: had RHO passed, how many spades would 1S show? Obviously 4 or more. Why would you allow the opposition to prevent you from showing four+ spades by an innocuous 1D overcall? How does that make any sense?

In contrast, after a 1H overcall, it’s normal (tho increasingly uncommon in expert circles) to have 1S promise 5+ and double to show 1S.

That may seem inconsistent but it is, in reality, not the least bit inconsistent.

After 1C (P) we bid 1H with 4=4 majors, but after the 1D overcall the opponents have given us an extra bid….we can double to show 4=4, so bidding 1M doesn’t show more than 4, although one could have a long suit…it isn’t limited to four cards.

After 1C (1H), again the opponents have given us another bid beyond what we’d have if they’d passed. It behooves us to take advantage of that extra call and the traditional way is to use double to show precisely four spades and 1S to show 5+.

These days many expert and some advanced players use different methods.

One early variant on the 1m (1H) sequences was (and for some still is) for double to deny 4+ spades. It shows values to bid but an inability to bid notrump or 2/1 in a suit or to raise partner. Say it went 1D (1H) and I held Kxx xx xx KJxxxx. I could pass but the auction could get uncomfortably high before I get another chance. I’m too weak for a traditional 2C bid. So I double, if that denies 4 spades or the ability to do anything more definitive.

Another and, these days, increasingly popular approach is for double of 1H to show either 4 or 5 spades: with 6 and the values to bid (by which I mean a nice 5 count or better) bid 2H.

Similarly after 1C (1D) many experts play that 1M shows 4 or 5 and 2D shows 6+ hearts while 2S shows 6+ spades.

To add to your confusion, some experts play that 1C (1D) x shows 4-5 hearts, 1H shows 4-5 spades and 1S shows…well, that varies amongst partnerships but a common approach is that it acts as a puppet to 1N.

And so on. I’m not suggesting beginner or intermediate players use these methods, but I wanted to add some detail to mycroft’s excellent post

[pescetom]

 mikeh, on 2025-May-06, 12:55, said:

Mycroft is exactly right. Think about it this way: had RHO passed, how many spades would 1S show? Obviously 4 or more. Why would you allow the opposition to prevent you from showing four+ spades by an innocuous 1D overcall? How does that make any sense?

I agree with you entirely that this makes no sense to a modern bridge player. My only contestation of Mycroft (and I am pretty sure he fully understood) was a precisation on the "historical" assertion... a good part of Europe historically played that after interference, 5 cards were necessary.
Even as recently as 40 years ago, see the (very logical and in many other aspects surprisingly modern) "Logic of Natural Bridge" by Franco di Stefano in 1987.
Hard today to see much sense in it, but then the opposition was much less aggressive in interference and tended to have the goods.
I've no idea what was going on elsewhere at the time, but FWIW Goren's New Bridge Complete of 1985 gives just two examples of 1C (1H) ?, one with S Kxxxx and 6 HCP ("Pass") and one with S AQxxx and 9 HCP ("Respond 1S. Your 9 points and 5-card suit fully entitle you to have your say in the auction"). If an example with a 4 card response was on his radar then he apparently couldn't find space in 701 pages for it.