A strange one, for sure.
After the hand was played, cards returned to board but before the next round was called, the defenders realized, in discussing the hand, that the declarer had revoked.
The declarer did not agree and the dummy couldn't remember (!). One declarer (very good memory and very honest - ex-director of the club) explained card by card the play.
The declarer said "I don't remember it that way" but had no other explanation of how the cards had been played. Both defenders agreed (of course) on the way things had gone.
The defender said:
"10 of clubs lead, won by K in other defender's hand (agreed by all), Jack of hearts lead, ducked by declarer, allowed to win the trick (dummy had two small hearts).
Next heart lead, trumped by declarer (diamonds trump).
Next few tricks and then a heart lead again, won by declarer with the Ace he should have played on the first trick (he having only two hearts also).
So, 3 diamonds making 4.
Scored and then director called. I believe that it is still a revoke since it was the last hand in a round and the next round was not called yet. But the penalty? Since the declarer doesn't agree? But has no other explanation except "I wouldn't have let the first heart ride" kinda bewilderingly.
I thought a one trick penalty (since he seems to have revoked and later had the Ace left to play and win a trick) was in order with an adjustment if necessary later.
However, he made 4, would have made 4 if he had played correctly, so is making 3 fair when he doesn't agree? I don't know what to do. I am a fill in director and haven't had this come about before.