In Craig's defence I clarified the problem description after he posted :)

I can certainly understand bidding 1N on this hand, but I don't get any doubt about whether it's ‘heavy’. I bet you could remove a K and Q from this and still find a majority in favour of protecting.

Presumably one of those places being spades?

I'm probably guilty of inventing a bid to fit my hand here, but it seems to me that:

a) With 5-5 spades and another, you don't lose much by bidding 3S, and might gain from the extra bidding space
b) With a single-suiter with spades you don't lose much by bidding 3S, and might gain from the extra bidding space
c) With 4 spades and equivalent values you will normally be able to double (if the majority are doing it here on 3 spades and a void it's hard to imagine many comparable 4-spaded hands where they wouldn't)
d) One of the most popular standard responses to a 1N opening is a jump to show (31)(54) or (30)55, and that seems almost as valuable here

So although it seems too specific a case for all but the most system-heavy partnerships to prediscuss, I feel like there's a case that the (hilariously optimistic) ‘common sense’ meaning could be ‘three places’, specifically with a spade tripleton. I guess with 31(54) double is always going to look good, so maybe it should specifically be 3055 or 30(64).

I wouldn't have had the guts to try it at the table, though.

4N seems unambiguous (which isn't to say it worked on this board, lest I bias anyone :), but is there a common sense meaning to 4H in this position?

I didn't think of this as much of a problem either, but a friend has convinced himself that the hand is ‘too good’ for 1S and is unpersuaded by my arguments otherwise, so I wanted to add some wisdom of the crowds to the case.

I thought about this at the time, and eventually decided that if we were going to set up the hearts we might well need our 2.5 outside entries, so the risk of getting rid of one of them was too high.

In the event I was wrong - P had QTxx Qx and out, and we needed to cash out to beat the contract. But I'm still not sure of a good way to judge which was the most likely scenario.

My minority is even minor-er :P

Yup. We ended up selling out to 2S-1, with 4♣ making, and both thought we should have bid up.

'KQxx xxx xx AQJx would be classical minimum values.'

I think I'd feel happier about doubling with that - it looks like a hand with substantially better ODR than ours.

Well I passed this for similar reasons and got a bad result when opener rebid 1N and I had to pass that out.

That's an auction where X obviously rates to be a winner (subject to P having 4 spades), but I struggle to think of any others - if the opps bid on freely, I'll be upset at having helped them pinpoint the honours (esp at MPs), and if LHO rebids 2-red I'm willing to X if it comes around to me. I can't imagine 4♠ being a sensible sac against 4♥, so it seemed to me like an X now was trying to hit too small a target.

I suppose I wouldn't be thrilled about defending 2♣ if that came back to me.

It's unlikely to be true for about 50% of the pairs in *any* field

So you want to make a bid on the grounds that no-one knows what it means?

On most hands where the club suit is relevant, I would expect 3♣ to make it harder for P to evaluate his hand, not easier. As Alan mentioned, QJx would look excellent, also Kxx would look good, Jxx promising, and x or xx would look rubbish.

Once in a while it might deter the opps from leading from Ax (I don't know what opps you have who'd be leading from Kx or Qx without the active deterrent), but other times P might raise on four-card holdings, telegraphing the lead for the guy holding four of the suit.

Sure, the worst slam I've seen was 0%, but I don't think they're a great benchmark ;)

I make it closer to 32-33% fwiw, depending on how much a good break in one suit improves the chances of a good break in another

As for useful systems, I'm still partial to my own *cough*Fantunes*cough* variant, which lets you open this a natural 1♦, show a strong hand over P's natural 1♥ response, hear a negative from P, and then continue with a natural and forcing 3♣. That would elicit a little shiver of joy when you realise how everyone else's auctions would have started.

The actual auction continued:
4♣ 5♣
6♣

Partner put down this beauty:

xxxx
xxxx
x
Jxxx

Certainly a better contract than 6♥, but that was little consolation for the predictable -1.

I bid 6♣. Partner put down this beauty:

xxxx
xxxx
x
Jxxx

It ‘had play’, but that was little consolation for the predictable -1.

P had something like x xx xxxx AJTxxx. When I passed as per the current majority, he doubled and we took them for 300 instead of bidding our cold slam.

In retrospect I feel like I should have bid - he's quite likely to have a spade void on the opps' bidding and the club ace on his own, and either makes slam look reasonable - he surely doesn't have two spades, and even in Acol would raise with 3 hearts, so he's got 10+ cards in the minors - and we can be fairly confident he doesn't have a single suiter with diamonds, so a 9 card club fit is strongly odds on, which should give us decent prospects of setting up the hearts even on a 4-1/4-2 split

Richard's right.