Having looked through several hundred suit fabric samples dating from the late-teens to the early-1960s, I've noticed that the popular 1950s "Atomic Fleck" was around long before it ever came under that name. My 'study' has shown that extremely similar fleck patterns can be found as early as the late-teens.
To demonstrate this, let's play a game.
Below are 7 fabric samples that could be considered Atomic Fleck. Some of these samples date from the early 1920s while the rest date from the 1950s. They are all disorganized and it is your task to identify from which era each sample comes. Let's see if we can tell what is 'real' Atomic Fleck and what is not. Leave your guesses in the comments.