At trick 2 I decided to finesse the Queen of hearts. The problem however is if you play the King, then the 10 and it loses to the Queen, South can switch to a spade and your hand is now cut off from dummy with the diamonds still blocked.
I therefore played the 10 of hearts, keeping my King as an entry back to my hand. The 10 of hearts was covered by the Queen and Ace so I am now in dummy. So far so good.
I now unblocked the diamonds as the best chance of a twelfth trick is for the Jack to fall in the first three rounds. At this stage it would have been nice if I could have ducked a spade for another chance of 12 tricks. However, the problem is that the defence could play back a club and that would be my last time in dummy with no access to the Jack of hearts. I therefore played a heart to my King and cashed the King of diamonds. The Jack did not appear but both defenders followed suit.
Next attempt was to play for a squeeze on North. He had already shown up with five clubs, three diamonds and two hearts. He seemed keen to cover my 10 of hearts (definitely the right thing to do) so I hoped he had four hearts (in which case he would have a singleton spade). North would then be squeezed between hearts and clubs when I played off Ace, King, Queen of spades. Unfortunately when North followed to a second round of spades, that plan went out of the window and I was doomed, ending up losing a diamond and a heart for one-off.
There was a winning line...
Everything was fine up to the play of the King of diamonds but now instead of cashing three top spades, a club towards the Ace squeezes South in three suits. He cannot part with the Jack of diamonds, discarding a heart sets up the fourth heart in dummy and if he lets go of a second spade, all my spades are good.
There is no escape. If South discards a second spade, AKQxx opposite a singleton yields five tricks without a loser! If South discards a heart, he becomes squeezed a second time between a spade and his Jack of diamonds. Quite incredibly there are now 13 tricks!!
If he throws his Jack of diamonds, at least he holds the contract to 12 tricks as he will now either make a heart or a spade.
If the cards had been as per the line I had played for with North holding four hearts, South would not now have been squeezed on the Ace of clubs and this second line of play would have failed. However I think this second line is more likely to succeed.
A third line of play that is maybe even better is to play a spade from dummy after unblocking the diamonds instead of playing a heart to the King. If you next cash AKQ of spades and see North show out on the third round, you can now lose a spade to South who has no clubs to mess up your communication with dummy. He therefore has to return a red card which you win in hand but you can now make a small spade for your twelfth trick. The advantage of this line of play is that had North shown up with a singleton rather than doubleton spade, you could have switched to the squeeze play that I tried to do.
The other team also made 11 tricks but they were only in 3NT so we lost 11 IMPs on the board. Had I made 6NT, we would have gained 11 IMPs so this was very expensive!