RKC Blackwood - an introduction
 

Along with Stayman, we're all familiar with the Blackwood convention - it's a way of finding out how many Aces partner has when you're looking for a slam in a suit. Or it used to be. Nowadays most players prefer the Roman Key Card version, or RKCB for short. Someone had the bright idea that as well as knowing how many Aces we have, it's also very useful to know (if you haven't got them yourself) whether partner holds the King and/or Queen of trumps. RKCB therefore deals with six elements instead of just four: five so-called 'key cards' (the four Aces plus the trump King) and the trump Queen. 

So how does it work? You start in the normal way: once a suit is agreed, 4NT signals a Blackwood enquiry. And these are the standard responses:

5♣ I have 0 or 3 key cards
5♦ I have 1 or 4 key cards (in either case, it should be pretty obvious which of the 0/3 or 1/4 meanings applies)
5♥ I have 2 (or, very rarely, 5) key cards and I don't have the trump Queen
5♠ Ditto - 2 or 5 key cards and the trump Queen as well.
 

The auction so far ...

What's happened on this hand so far? You replied 2♣ to your partner's opening 1♥. Wot? some will ask. Just 2♣? With all those points? The answer is an emphatic yes: just 2♣. Sure, you're wondering about a slam, but you have no idea yet which slam you want to be in. First you need to know more about your partner's hand, and to do that a normal response is all you need: 2♣ denies 4 hearts and promises at least 10 points and at least 4 clubs and - crucially - it unconditionally requires your partner to make another bid. And after that second bid, the position will be much clearer and you'll know where you want to be heading. Take it slowly. If you start jumping all over the place it'll just be guesswork.

And partner's second bid is indeed very informative: 4♥ is a bit like 2♥ - it's just an ordinary opening hand in strength, but with lots of hearts - probably 7. With a stronger (16+) hand and 6 good hearts, she would have jump-rebid 3♥, which would really have got the juices flowing, but we are where we are: you have a heart fit with partner, who has just the normal 11-15 points. Is the heart slam on?

Well, it could be, certainly. If partner has ♥AKQ and the ♣A, you might even make the grand slam. And if you're missing one of those, you're probably fine for the small slam. How to find out?
 

... and going forward

This is a perfect time for RKC Blackwood. It can tell you about all four of the crucial missing cards - three key cards + the ♥Q - and partner's reply should guide you to the right place. So you bid 4NT ...

... and partner replies 5♥. What does she have and what's your final contract going to be?

5♥ tells you that she has two key cards but doesn't have the ♥Q. Not enough. You're likely to lose a trick to the missing key card and also possibly to the ♥Q. No slam. Pass. 
 

What happens?

Take a look at the whole deal. As so often happens, the final result depends on the opening lead. If West leads a club you're losing two tricks: one to the ♣A and one to the ♥Q. But if she leads a diamond, you're making a slam: win trick 1 in hand, cash the ♥AK, then cash the three top spades discarding your losing club on the third round. 

But the main point is that you don't want to be in the slam. RKCB is a great way of finding slams, but it'a equally good at helping you to avoid slams that don't make. *
 

On the night

On the posh night, three pairs managed somehow to jump into 6NT, all going off. One was in 3NT+2. And the other two tables were in 4♥ and 5♥, both making 12 tricks - even though one of them got a club lead! How? I imagine declarer led dummy's ♥2 and East played low , allowing declarer's ♥10 to win the trick. Nothing venture, nothing win! 

In AP, two pairs didn't fare particularly well in 3NT. One made 4♥ and one (post-RKCB?) stopped in 5♥ - making 12 tricks on a diamond lead. Two others were in 6♥ - both sadly got a club lead and went one off.

cj

* You may be wondering how you find out about the trump Q if partner replies 5♣ or 5♦ instead of 5♥ or 5♠. It's all done by you bidding the next suit up, but that's a complication we don't need in this HOTW. Ask me if you want to know more ...