This is a very tough question, in any 'natural-based' method, whether it be 2/1, SAYC or Acol.
Your choices seem to be:
3
♠
4
♠
4
♣
4
♦
4
♥
5
♣
5
♦
3
♠ is out, as simply not enough. You definitely have to be in game here, so you cannot make a bid that will often be passed.
4
♠ at least reaches game. The lack of a
♥ raise is not as worrying as it would be if we were at unfavourable: East may hold several
♥ but with an aceless, flat hand, he won't be in a hurry to risk 800 or more. So there is a good chance that partner has the 2
♠ that I'd like him to hold in order to make
♠ a safe contract.
Clearly, 4
♠ has even more going for it at Acol, since you have not one but two more
♠ than partner was entitled to count.
4minor: these bids are a little more encouraging than 3
♠, in that you may hit a 1=2=5=5 or so, in which the stiff
♠ is a potential asset, rather than a clear negative as it would be over 3
♠. However, the bid does not itself send the message that you have strength: you might even be 5=2=3=3 with horrible
♠ and a minimum. So these bids are less attractive than 4
♠, the leader so far.
4
♥: this gets the job done in terms of getting us to game. It also preserves the chances of reaching
♠: my view is that partner should clearly bid 4
♠ with Hx in that suit unless he has a big hand. Our possession of aces suggests that he will not push towards slam unless we have a good play for such a contract.
The main downside of 4
♥ is that he may not bid 4
♠ with xx: indeed, I would like to hear from acolites as to whether 4
♠ is even permitted on this auction with xx (Frances?). There is a valid and appropo saying here: 'game before slam', so partner should not take your 4
♥ as a slam move, but as an effort to find the best game.
Another, lesser problem with the cue-bid is that you are, in my view, minimum for the call. However, you are allowed to be minimum
5minor: too arbitrary. Partner may well be 2=2=4=5 or 2=2=5=4 or so, and now you are guessing as to the correct suit: partner will not 'correct' on these auctions.
One I left out: 4N
What is 4N? If I hold a big balanced hand with
♥ well stopped, I might be taking the number on offer at this vulnerability. If I held a solid, running suit, with a
♥ stop?? Maybe AKQJxxx Kxx Ax Q. Could it be for the minors? If so, maybe it is a good choice.
Inviting a NT slam so as not to get a
♥ ruffed?
Anyway, if the person thinking of making a bid does not know what it should mean, then he should not make the bid
Believe it or not, I would actually go through this sort of 'differential diagnosis' exercise at the table: it takes far longer to type/read this than it does to think it.
Perhaps not surprisingly I have been accused of being a 'thoughtful' player: a.k.a. slow.
So I go with 4
♥, with a strong second choice of 4
♠, and (because I do not know Acol very well) I'd probably reverse the order of those calls if I was filling in in an Acol partnership.
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari
pass - 1♠ - 3♥ - X
pass - ?