Rubber johnny

sad I know, but despite some illuminated suggestions I still have no idea where this term came from. help?

RUBBER JOHNNY - "The Dictionary of Contemporary Slang" by Tony Thorne (Pantheon Books, New York, 1990) says: "rubber, rubber johnny n. - a condom. The first version is international English. The second is British. Johnnie, Johnny and Johnny-bag are synonyms."

The Oxford Dictionary of Modern Slang by John Ayto and John Simpson (Oxford University Press, Oxford, New York, 1992) says the term "rubber johnny" dates back to 1980.

"British English A to Zed" by Norman W. Schur (HarperCollins, New York, 1987) says "johnny" is a term for "guy." I think the terms "rubber johnny" and "johnny" have their roots in the slang term "johnny" for "guy."

And that's all I know about that.

Just shows how inaccurate reference books can be The Oxford Dictionary of Modern Slang by John Ayto and John Simpson" have got it quite wrong in that, to my certain knowledge, we used the term "rubber jonny", "french letter" or "Durex" to refer to a condom in the early 1950 in East London and we didn't invent the phrases either.