This hand came up in Colchester A's last league game of the season. We won the match and the league but only reached 6♦ on this hand which could have been a costly error. I got everything right except the last link in the chain.

When I picked up 20 points as South I didn't expect to hear partner open.

The first key step is to bid 2♣. This hand could be ending up anywhere and I need to give partner a chance to tell me more about their hand.

Their 3♣ rebid is great news. It tells me they started with 5 Diamonds (otherwise they're rebidding No Trumps). It also tells me they have at most 15 points (with more they aren't going to risk my Passing 3♣).

Now I know we want to play in 6♦ provided we aren't missing two Aces. I can use Blackwood to check because if partner only has one Ace we can safely stop in 5♦ .

However we were playing Roman Key Card Blackwood which asks how many of five key cards do you have? The key cards are the four Aces and the King of the agreed suit (in this case Clubs). So partner's 5♣ bid says I have either 0 or 3 of those key cards.

I was so busy frantically checking that partner could not have opening points without having at least one of the five key cards (and therefore must have three) that when I had worked that out I heaved a mental sigh of relief and bid 6♦ .

I missed the final step. I didn't bid 5 NT because I thought that 6♥ took us too high if we were missing a King. That was poor thinking because even missing one King I can count thirteen tricks, namely 5 Diamonds, 4 Clubs (partner has shown the ♣ K ), ♥ A,♠ A, whichever Major Suit King partner has, and the Queen that goes with that King