That historic occasion, which West Ham lost to 2-0 Bolton, was of course the first FA Cup final at Wembley, and crowds which had swelled to 200,000 were largely controlled by a policeman on a white horse named Billie.
It may be surprising to learn, for those who think that in those days only local players played for the Hammers, that even 80 years ago West Ham's scouting tentacles had spread far enough to bring a couple of Geordies to east London!
Recalls Dorothy vividly: "Dad was right full back and Billy Henderson was left full back; they both came from the little village of Whitburn.
"Dad wouldn't play for local teams, and look what it did for Gazza!"
Then, as now, playing football for a living was a privileged, and well paid profession, and Dorothy says: "I think he earned £7 a week in the summer and £15 when they played.
"A lot of people only earned £3 even in the 30s."
"We used to come and live in Sheperd's Bush in the football season until we were kids and then had to go to school in the north east.
"It was very hard times in those days but he was a very good footballer.
"It was a £600 transfer when, as dad told me, in those days £200 was a good transfer fee to pay."
Jack continued in the game after his playing days were over by scouting for a former playing colleague, George Kay, who went on to manage Saturday's opponents Liverpool.
When the museum eventually expands - as it will - the contracts Jack signed are likely to be on display.
Dorothy thoroughly enjoyed her visit to the museum, and says proudly: "I am an adopted Geordie West Ham fan!"