Suit preference

The auction (Dealer North, E/W Vul):

A little comment about the auction:
North’s hand with its 17 HCP, a solid five-card suit and seven quick tricks is too good to open 1NT. His Double after West’s overcall shows three Spades and a good hand. South’s jump to 3♠ indicates a five-card suit and 8-9 HCP.

The start of the play: West leads the Diamond Ace: five, two, four. West continues with the King: eight, nine, Jack.

How declarer wins his contact: East’s Diamond two at trick one shows count. When he plays the nine on the second round, it is obviously his highest card and a clear suit preference: East certainly wants to signal that he has the Queen of Hearts. Our Santa Claus is very attentive and disciplined, so he switches to the eight of Hearts, won by the Ace in dummy. Declarer plays a trump to his King and West wins with the Ace and insists with another Heart. Dummy’s King wins the trick and declarer can claim the rest: after two more rounds of trumps, he plays a Club to dummy and discards his Heart loser on a Club. Do you see how this contract could have been beaten?