Weighing 500lbs, the cake contained fruit sent from all corners of the Empire. Each of its four tiers was made up of two cakes layered with marzipan.
"That was quite a cake," said Mr Williams. "It was top secret. No one was allowed into the building where they were making the cake, even though everyone wanted a peek."
Mr Williams also helped to design the first Jaffa Cake, on which a simple combination of apricot pulp, sugar and tangerine oil combined to form the sealed layer of jam.
Hygiene manager Frank Ahluwalia, 54, has worked his way up from the factory floor over 37 years. He said: "This place was always a nice family company, and it has absolutely done me well. I can't fault it."