Ultimately, the winner at sport is he who makes the last-but-one mistake. That's what happened here.
I used, regularly, to take part in the Southend & District Chess League Knockout Championship. In 1984 I had a better run than usual and got to the semi-final. My opponent and I agreed a date on which to play the match but then, the day before, I got mumps and was out of action for almost a month. I phoned him to rearrange but he said he was going to claim the game. I then phoned the league chairman who insisted on a postponement and, some weeks later and me three stone lighter, we sat down to play.
It was a Sicilian Defence and a very well-balanced game in which we both got into horrendous time trouble. From the start we each had to make 30 moves in 75 minutes, but thought so long about a complex position that with about 2 minutes left we each had about 12 moves to make. Unwisely, I sacrificed a piece whereon an almighty melée took place and loads of pieces were exchanged. The air cleared, I was still a knight down and in a totally lost position. He said "That's 30, isn't it?", meaning the number of moves we had recorded. I replied that I made it only 29 but he said "I'm sure it's 30" and he sat and had a think. A few seconds later his flag fell. "Your flag's down!" said I to which he replied "But we've made 30 moves."
"I'm not sure that we have. I'd like to check."
So we stopped the clocks and set up another board and played through all the moves we had made. After 29 moves we reached the position on our original board. He couldn't believe it and kept looking at his scoresheet. I pointed out that he'd failed to write move 25 (the bottom line) of the game in its correct place, instead going to the top of the next column and writing the 25th move in move 26's place.
We played through the game once more to ensure that we hadn't made any mistakes and 29 moves it was. He was livid but I certainly wasn't going to be at all generous to someone who tried to claim the game when I was ill. To be fair, I was still ill when we played. It was years before he spoke to me again.
As luck would have it I played a much higher rated player than myself in the final and won handsomely, thereby becoming the League's Individual Champion for the only time in my career.
My opponent from the semifinal eventually took to Buddhism and gave up chess because of all the death that ensued in every game. I still see him occasionally cycling around Southend.