Edward Scher (1907) Vs Samuel Englard (1826)

I blame the cruel problem of time pressure (with only 3 minutes left on my clock and my opponent whom already stopped annotating the game so as to be able to save time, whereas I was forced to waste precious time meticulously recording each move so as to be able to appreciate for my readers the full game as it was played) as the reason for my blundering with move 73.a4??. Instead I should have played the following winning variation: