This is what ChatGPT tells us:
"Odd John" is a term that can be found in literature, and it refers to a specific character from a science fiction novel titled "Odd John" by Olaf Stapledon, published in 1935. In the novel, "Odd John" is the nickname given to John Wainwright, a highly intelligent and unconventional human being who possesses extraordinary mental and physical abilities. He is considered odd or different from typical humans due to his advanced traits.
The book explores themes related to human evolution, superintelligence, and the challenges and societal implications of individuals who are vastly superior to the average human. "Odd John" has had a lasting influence on science fiction literature and has been considered a classic in the genre.
So, when the term "Odd John" is used in a context like the one you provided from the 1961 article, it's likely making a reference to this novel and using it metaphorically to suggest that something is memorable, unique, or stands out in a notable way, just as the character John Wainwright (Odd John) did in the book.